PH-F-03: The Renewed US–Philippines Alliance: EDCA Expansion, South China Sea Crisis, and the Squad Architecture (2022–2025)

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1. Key Takeaways

The 2022–2025 period constitutes the most significant structural expansion of the US–Philippines alliance since the 1951 Mutual Defense Treaty itself, and represents a deliberate Philippine sovereign choice rather than a passive realignment. Under President Ferdinand R. Marcos Jr., the Philippines moved within twenty-four months from a Duterte-era posture of public alliance hedging — the 2020 Visiting Forces Agreement (VFA) termination notice, the rhetorical China embrace, the rejection of "joint patrols" with the United States — to the announcement of four new Enhanced Defense Cooperation Agreement (EDCA) Agreed Locations on 2 February 2023, the signing of the first ever Bilateral Defense Guidelines on 3 May 2023, the explicit extension of the Mutual Defense Treaty's "ironclad" commitment to coast guard vessels and aircraft in the South China Sea, and the construction of a quadrilateral "Squad" defence architecture with Japan and Australia. Each step was contested domestically — by former President Rodrigo Duterte, by Vice-President Sara Z. Duterte-Carpio, by Cagayan Governor Manuel N. Mamba, and by elements of the pro-China-balancer left — but the pivot has held through three years of sustained Chinese maritime pressure, a coalition rupture, and a US presidential transition.
The five new EDCA Agreed Locations announced on 2 February 2023 — Naval Base Camilo Osias and Lal-lo Airport (both in Cagayan), Camp Melchor F. Dela Cruz (Isabela), Balabac Island (Palawan), and Antonio Bautista Air Base (also Palawan) — bring the total to nine and have a geographic logic that is unmistakably bi-directional. Three of the four new sites cluster in northern Luzon — Cagayan and Isabela — within reach of the Bashi Channel separating the Philippines from Taiwan, which is the principal maritime chokepoint a Taiwan Strait contingency would activate. Two sites — Balabac and Antonio Bautista — sit in Palawan, the Philippine province nearest the contested Spratly features and the South China Sea sea lanes. The previous four sites — Antonio Bautista Air Base (in fact already on the list since 2016 in a different functional category), Basa Air Base (Pampanga), Fort Magsaysay (Nueva Ecija), Lumbia Air Base (Cagayan de Oro), and Mactan-Benito Ebuen Air Base (Cebu) — had a less directional pattern. The 2023 expansion's geography acknowledges what the US has acknowledged before Congress: northern Luzon is positioned for Taiwan, and Palawan is positioned for the South China Sea.
The 3 May 2023 Bilateral Defense Guidelines are the first such joint defence document ever produced in the seven-decade history of the alliance. Earlier expansive readings of the MDT — the 2014 EDCA, the 2019 Pompeo "Pacific" clarification, the 2021 Austin–Lorenzana "ironclad" affirmation — had elaborated specific elements without producing a comprehensive doctrinal document. The 2023 Guidelines accomplish three things in writing: they confirm that an armed attack on either party's armed forces, coast guard, or aircraft "anywhere in the South China Sea" invokes the MDT; they identify cyber, space, and grey-zone operations as in-scope; and they commit both sides to deeper combined planning, training, and interoperability under a Joint Strategic Planning Construct. The document's existence — and its accessibility on US Department of Defense and Philippine Department of National Defense websites — closes the ambiguity that has constrained alliance deterrence since the 1951 signing.
The South China Sea crisis cycle has acquired a distinctive Philippine operational signature — the "transparency" strategy of public attribution, real-time documentation, and named-and-shamed Chinese vessels — built around the Philippine Coast Guard (PCG) under Commodore Jay Tarriela's communications direction. The strategy reversed the Duterte-era preference for "quiet diplomacy" by inviting media — local and international — onto resupply missions, by releasing video and photographic documentation of Chinese water-cannon, ramming, and laser incidents within hours of occurrence, and by attributing the People's Liberation Army Navy, the China Coast Guard (CCG), and the maritime militia (the People's Armed Forces Maritime Militia, PAFMM) by hull number. Romualdez–Tarriela transparency is itself a strategic-information instrument: it imposes reputational cost on Chinese coercion, supplies allied governments with evidentiary material for joint statements, and constructs the public narrative within which legislative appropriations, alliance commitments, and ASEAN positioning are negotiated.
The 17 June 2024 boarding of Philippine Navy resupply boats at Second Thomas Shoal — known in the Philippines as Ayungin Shoal — was the most violent encounter between Chinese and Philippine forces since the 2012 Scarborough standoff and brought the alliance closest to MDT activation since 1951. CCG personnel boarded the resupply RHIBs (rigid-hulled inflatable boats), confiscated weapons, damaged equipment, and one Philippine Navy sailor lost his right thumb in the encounter. The incident triggered a fortnight of intense US–Philippines coordination, a public statement by US Secretary of State Antony Blinken reaffirming the MDT, and the diplomatic process that produced the 21 July 2024 "provisional arrangement" allowing Philippine resupply of BRP Sierra Madre under specific conditions. The provisional arrangement has held — with limited turbulence — through subsequent resupply runs, but the structural disagreement underlying it remains unresolved.
The "Squad" architecture — the US–Japan–Australia–Philippines quadrilateral that emerged in 2023–2024 — represents a meaningful innovation in Indo-Pacific security architecture beyond the established Quad (US–Japan–India–Australia) and beyond AUKUS. The first Squad defense ministers' meeting in Hawaii on 2 May 2024 produced an unprecedented four-way joint statement on the South China Sea; the 11 April 2024 trilateral leaders' summit at the White House between Biden, Marcos, and Kishida formalised the US–Japan–Philippines triangle within the architecture; Australia's defence-personnel rotations to the Philippines under the Status of Visiting Forces Agreement and the joint maritime cooperative activities (MCAs) since November 2023 give the architecture operational content. The Squad's defining feature — Philippines as full strategic principal rather than as US client — is the structural inversion of the Cold War alliance pattern.
The Mid-Range Capability missile system (the "Typhon"), deployed by the US Army Pacific to northern Luzon in April 2024 for the Salaknib and Balikatan exercises and subsequently retained on a rotational basis, is the single most strategically consequential US capability deployment to the Philippines since the 1992 base closures. The Typhon is capable of firing the Tomahawk Land Attack Missile (range exceeding 1,500 kilometres) and the SM-6 (which has anti-ship variants). Its presence in Cagayan or Ilocos Norte brings major Chinese coastal targets — including Hainan Island's naval facilities and continental China itself — within reach of US ground-based fires. China's diplomatic protest was sustained and at the foreign-minister level; the deployment's open-ended retention, despite Chinese pressure, signals a US calculation that capability presence outweighs reassurance value. The strategic significance of the Typhon deployment will likely be the dimension of the 2022–2025 expansion that future histories most heavily emphasise.
The 8 November 2024 enactment of the Philippine Maritime Zones Act (Republic Act 12064) and the Philippine Archipelagic Sea Lanes Act (Republic Act 12065) translates the 2016 Permanent Court of Arbitration award into operational Philippine domestic law for the first time. The Maritime Zones Act codifies the Philippine territorial sea, contiguous zone, exclusive economic zone, and extended continental shelf in conformity with the United Nations Convention on the Law of the Sea (UNCLOS) and explicitly references the 12 July 2016 arbitral award as binding. The Archipelagic Sea Lanes Act designates three sea lanes for international transit through the Philippine archipelago, exercising the Philippines' right as an archipelagic state under UNCLOS Article 53. China formally protested both laws, declared them "null and void," and within four days announced "baselines of the territorial sea adjacent to Huangyan Dao" — the Chinese name for Scarborough Shoal — codifying a contrary maritime claim. The lawfare exchange establishes that the legal-instruments layer of the contest is now active and bilateral.
The Balikatan exercise series has scaled dramatically in personnel and complexity across the 2022–2025 period — from approximately 5,000 combined personnel in 2022 to roughly 16,000 in 2023, 16,700 in 2024, and 14,000 in 2025 — and has shifted from rear-area training to forward, scenario-realistic, multilaterally inclusive operations. Balikatan 2023 introduced live-fire sinking of a decommissioned target ship; Balikatan 2024 included a multilateral maritime exercise in the Bashi Channel and a Batanes amphibious component; Balikatan 2025 incorporated the Typhon and a full-scale defence-of-archipelago scenario. Salaknib (army-army), Kamandag (Marine Corps), Sama Sama (navy multilateral), and Maritime Cooperative Activities supplement the annual rhythm. The exercise tempo is not a cosmetic alliance signal — it is the principal mechanism through which combined operational capacity is built.
The Duterte-era China posture was structurally repudiated, but pockets of pro-China-balancer critique persist, locate themselves within the constitutional opposition, and constitute the principal domestic-political counter-narrative to the Marcos alliance turn. Vice-President Sara Z. Duterte-Carpio's 2023–2025 statements on alliance affairs — restrained until the coalition rupture, more pointed afterward — repeatedly characterised EDCA expansion as importing US conflicts into Philippine territory. Former President Rodrigo Duterte (until his 11 March 2025 ICC arrest and transfer to The Hague) maintained that the South China Sea contest was a "rich man's quarrel" the Philippines could not win and should not provoke. The PDP-Laban congressional bloc, the Hugpong ng Pagbabago regional party, and the harder-left Bayan Muna remnants articulate variants of the non-aligned position. The mid-term Senate result of May 2025 (covered in PH-D-05) preserved a Marcos-aligned majority on alliance questions, but the contest is not over: alliance legitimacy in the Philippines is always one bad incident or one bad presidency away from reopening.
The Trump-2 transition in January 2025 stress-tested the alliance and the test was provisionally passed, but on transactional rather than ideological terms. Defense Secretary Pete Hegseth's 28 March 2025 visit to Manila — his first to Southeast Asia in office — produced a reaffirmation of the MDT, a confirmation of EDCA continuity, and the announcement of additional capability deployments. The Marcos–Trump 31 January 2025 phone call (the first between the two leaders since Trump's January inauguration) was characterised by both sides as productive. But the 2 April 2025 "Liberation Day" tariffs imposed a 17 per cent reciprocal tariff on Philippine exports, the Philippines' second-largest export destination is the United States, and the alliance's economic-security dimension entered a new period of tension. The structural reading: under transactional alliance management, security cooperation is sticky but economic linkage is contestable.
The forward view, into 2026 and beyond, identifies four open questions whose resolution will determine whether the 2022–2025 expansion consolidates as the durable architecture of US–Philippines alliance for the 2030s or whether it proves a high-water mark that subsequent administrations recede from. The capability trajectory — whether the Typhon deployment becomes permanent and whether indigenous Philippine capabilities (radar, fast attack craft, drones) scale to offset the asymmetry. The crisis-cycle trajectory — whether the 17 June 2024 incident represented the high-water mark of CCG escalation or whether 2026–2027 produces a more violent encounter that triggers MDT activation. The domestic-politics trajectory — whether the 2028 Philippine presidential election produces a successor who continues the Marcos posture or who restores Duterte-style hedging. And the structural trajectory — whether the semiconductor-supply-chain logic, the San Bernardino–Surigao Strait chokepoint geography, and the Chinese island-building consolidation produce a stable equilibrium of mutual deterrence or a moving-equilibrium contest of attrition.

2. The Baseline Inherited: From MDT 1951 to the Duterte VFA Reversal (1947–2022)

The alliance the Marcos Jr. administration inherited on 30 June 2022 was not a single instrument but a layered stack accreted over seven decades. Understanding the 2022–2025 expansion requires understanding what was already in place and what had recently been damaged. PH-F-01 supplies the long-arc treatment from 1898; this section condenses what is necessary for the 2022–2025 frame.

2.1 The Treaty Stack — MBA, MDT, VFA, MLSA, EDCA

The 1947 Military Bases Agreement (MBA), signed 14 March 1947 between Philippine President Manuel Roxas and US Ambassador Paul V. McNutt, placed twenty-three US military installations on Philippine soil under 99-year leases. The 1951 Mutual Defense Treaty (MDT), signed in Washington on 30 August 1951 by Philippine Foreign Secretary Carlos P. Romulo and US Secretary of State Dean Acheson, committed both parties to act against an "armed attack" on either party's metropolitan territory, Pacific island territories, or "island territories in the Pacific under their jurisdiction." The MDT is the bedrock instrument; every subsequent layer operates beneath it.

The 1991 Senate rejection of the bases extension (Section 2.2 below) closed the MBA as a continuing arrangement. The post-bases reconstruction took eight years: the Visiting Forces Agreement (VFA), signed 10 February 1998 by Philippine Foreign Secretary Domingo L. Siazon Jr. and US Ambassador Thomas C. Hubbard, was ratified by the Philippine Senate on 27 May 1999 by an 18–5 vote during the Estrada administration. The VFA gave US forces a legal framework to enter the Philippines for exercises and operations without re-creating the bases regime. The 2002 Mutual Logistics Support Agreement (MLSA), signed 21 November 2002 under President Gloria Macapagal-Arroyo, allowed reciprocal logistics support, supplies, and services. The 2014 Enhanced Defense Cooperation Agreement (EDCA), signed 28 April 2014 in Manila by Philippine Defense Secretary Voltaire Gazmin and US Ambassador Philip S. Goldberg on the day of President Obama's state visit, authorised US rotational presence at Philippine "Agreed Locations" — facilities the Philippines owns and at which the US may preposition equipment, stage operations, and rotate personnel.

By 2022, the stack was MDT (foundational treaty), VFA (entry framework), MLSA (logistics), and EDCA (basing-equivalent). Each was a sovereign Philippine instrument, ratified or signed under Philippine constitutional process — but EDCA's constitutional status remained contested. The Supreme Court of the Philippines, in Saguisag v. Executive Secretary (G.R. No. 212426, 12 January 2016), upheld EDCA as an executive agreement rather than a treaty requiring Senate concurrence, on the ground that it implemented the MDT and VFA rather than creating new commitments.

2.2 The 1991 Senate Vote and the Post-Bases Architecture

The 16 September 1991 Senate vote — 12 votes against, 11 in favour of ratifying a new bases treaty — closed Clark Air Base (already destroyed by the 15 June 1991 eruption of Mount Pinatubo, which dumped ash up to a metre thick across the base) and Subic Bay Naval Base (formally handed over on 24 November 1992). The twelve senators who voted against ratification, led by Senate President Jovito R. Salonga, Senator Wigberto E. Tañada, and Senator Aquilino Q. Pimentel Jr., became known as the "Magnificent Twelve" in nationalist political memory. Article XVIII, Section 25 of the 1987 EDSA Constitution — drafted in conscious anticipation of this moment — required that "after the expiration in 1991 of the Agreement between the Republic of the Philippines and the United States of America concerning Military Bases, foreign military bases, troops, or facilities shall not be allowed in the Philippines except under a treaty duly concurred in by the Senate."

The 1991 vote established two structural features. First, foreign basing requires Senate ratification — a procedural moat that subsequent agreements (VFA, MLSA, EDCA) have navigated by being framed as something other than "bases." Second, the constitutional commitment to a non-bases architecture was not anti-alliance; it was anti-permanent-basing, which was the specific arrangement that had carried the colonial inheritance and Cold War tolerance for the Marcos dictatorship into the post-EDSA period. The Salonga generation's vision was a Philippines that could host allied military activity on terms it controlled, not on terms inherited from 1947.

2.3 The Duterte Period — VFA Termination, Suspension, Reinstatement (2020–2021)

President Rodrigo R. Duterte's relationship with the VFA — and with the alliance generally — followed an oscillating pattern that left the underlying architecture intact while producing sustained political damage to the alliance's legitimacy. On 11 February 2020, Foreign Secretary Teodoro L. Locsin Jr. formally notified US Ambassador Sung Kim of the Philippines' intention to terminate the VFA, with the 180-day termination clock to run from that date. The trigger event was the US revocation of a visa held by Senator Ronald M. "Bato" Dela Rosa, the former Philippine National Police chief who had implemented the early phases of the drug war.

The 180-day clock would have run to mid-August 2020. On 1 June 2020, Foreign Secretary Locsin notified the US that the termination was being suspended for six months — a suspension justified at the time as a function of the COVID-19 pandemic and "political and other developments in the region." The suspension was renewed on 11 November 2020 (another six months) and again on 8 June 2021 (another six months, to December 2021). The final disposition came during the 30 July 2021 Manila visit of US Defense Secretary Lloyd J. Austin III: Duterte announced on the eve of the visit that he was "fully restoring" the VFA. Locsin formally rescinded the termination notification.

Throughout the eighteen-month termination saga, the Philippine defence establishment — Defense Secretary Delfin Lorenzana, Armed Forces of the Philippines Chief of Staff General Felimon T. Santos Jr. and his successor General Cirilito E. Sobejana, and the National Security Council — maintained close working coordination with US counterparts. The 2016 South China Sea arbitral award (PCA Case No. 2013-19) had been domestically de-emphasised by Duterte personally but never repudiated; the Department of Foreign Affairs continued to invoke it in note verbales protesting Chinese maritime conduct. The Balikatan exercise series continued through 2020 and 2021 in scaled-down form (with COVID-19 protocols). EDCA's existing five sites — Antonio Bautista Air Base, Basa Air Base, Fort Magsaysay, Lumbia Air Base, Mactan-Benito Ebuen Air Base — continued to host US prepositioned materiel.

The Duterte pattern was, in retrospect, a stress test the alliance survived. The treaty architecture proved more durable than the head of government's hostility to it. But the damage to alliance legitimacy was real: Duterte's repeated invective against US officials (including President Obama, whom he characterised in profanity in September 2016), his September 2016 "separation" speech in Beijing, his pursuit of Chinese investment under the Comprehensive Agricultural Partnership and the Belt and Road Initiative, and his withdrawal of the Philippines from the International Criminal Court (16 March 2019) all positioned the Philippines as visibly hedging away from the US even as the bureaucratic alliance held.

2.4 The Strategic Inheritance Marcos Jr. Received in June 2022

The inheritance had four operative components. First, the treaty stack (MDT, VFA, MLSA, EDCA) was intact, with EDCA's five existing Agreed Locations functioning. Second, the US "Pivot to Asia" begun under Obama and the Indo-Pacific Strategy elaborated under Trump-1 and Biden had produced US institutional and capability investments — INDOPACOM force posture review, AUKUS (announced 15 September 2021), the Quad's 2021 elevation to leaders-level — that made the Philippines strategically valuable to Washington in ways that 2010 baseline analyses had not anticipated. Third, the 2016 South China Sea arbitral award was diplomatically dormant under Duterte but legally intact, available for reactivation. Fourth, the Chinese maritime pressure pattern — gray-zone harassment of Philippine fishermen, water-cannon incidents (the first major one, on 18 November 2021 at Ayungin Shoal), island consolidation in the Spratlys, the Scarborough exclusion — had continued without strategic pause, supplying the empirical basis for any incoming administration's recalibration.

Marcos Jr. did not need to construct the alliance from scratch. He needed to decide whether to maintain Duterte's public hedge or to align Philippine public posture with the private bureaucratic continuity. His campaign rhetoric had been ambiguous: in interviews during the 2022 campaign he characterised the 2016 arbitral award as a "Philippine victory" while simultaneously maintaining that he would pursue "good relations" with China. Whether he would lean toward Beijing — as the Duterte camp expected and the Chinese embassy at one point publicly hoped — or toward Washington was, on 30 June 2022, an open question. The answer arrived within seven months.

3. The Marcos Jr. Pivot — Posture, Personnel, and the February 2023 Inflection (June 2022 – April 2023)

3.1 The Inaugural Posture and the First Six Months

President Ferdinand R. Marcos Jr.'s 25 July 2022 First State of the Nation Address (SONA) signalled the direction without revealing its pace. On foreign policy, the President stated: "I will not preside over any process that will abandon even one square inch of territory of the Republic of the Philippines to any foreign power." The line was widely read in Manila as a coded reference to the 2016 arbitral award and to the South China Sea contest; it was reported in Inquirer, Rappler, and Philippine Star as a deliberate break from the Duterte-era rhetorical register.

Personnel decisions reinforced the read. Defense Secretary Delfin Lorenzana — a holdover Duterte appointee with consistently pro-alliance instincts — was succeeded by Carlito G. Galvez Jr. (former AFP Chief of Staff under Duterte but a career officer with deep US training ties) as Officer-in-Charge from July 2022 and as full Secretary by January 2023. National Security Adviser Clarita Carlos (an academic) was succeeded in February 2023 by Eduardo M. Año, a former AFP Chief of Staff and Interior Secretary who had been the AFP commander during the 2017 Marawi siege and worked extensively with US Special Operations counterparts. Foreign Secretary Enrique A. Manalo — a career diplomat — replaced Teodoro Locsin Jr. and re-emphasised the rules-based order and the 2016 arbitral award in public statements.

The first six months produced two diplomatic markers worth identifying. President Marcos visited Beijing for a state visit 3–5 January 2023 — accepting an invitation that had been outstanding since shortly after his inauguration — and met President Xi Jinping. The joint statement that emerged contained the customary language about "friendly consultations" on the South China Sea but did not produce the kind of strategic-direction shift the Chinese side had reportedly hoped for. The 5 January 2023 communique included an agreement on the establishment of a hotline between the two countries' foreign ministries on the South China Sea, a request the Philippines had pursued since 2018. The hotline was operationalised but proved to be of limited effective use in subsequent crisis incidents.

The second marker: a series of Philippine Coast Guard (PCG) public-attribution incidents in late 2022 and early 2023. On 6 February 2023 — four days after the EDCA expansion announcement, but in events that had been documented by the PCG over the preceding weeks — PCG Commodore Jay Tarriela released video footage of a China Coast Guard vessel using a "military-grade" green laser against a Philippine Coast Guard ship, BRP Malapascua, attempting a resupply mission to Ayungin Shoal on 6 February 2023. The video showed the laser causing temporary blindness to BRP Malapascua crew. The release — coordinated through Tarriela's X (then-Twitter) account and through Philippine media — was the first major instance of what would become the "transparency strategy" (Section 6 below).

3.2 The Austin Manila Visit and the EDCA Expansion Announcement (2 February 2023)

US Secretary of Defense Lloyd J. Austin III arrived in Manila on 1 February 2023 for a two-day visit. The visit had been preceded by months of bilateral working-level discussions on the implementation of EDCA, including the question of additional Agreed Locations beyond the original five. On 2 February 2023, after a meeting at Camp Aguinaldo with Defense Secretary Galvez (then OIC) and a separate meeting at Malacañang with President Marcos, the joint announcement was made: four additional Agreed Locations would be designated under EDCA, bringing the total from five to nine. The specific sites were not all announced on 2 February; Galvez stated that the locations would be finalised "in the coming weeks" pending consultations with local government units and final inspection.

The geographic identification proceeded in stages. By 3 April 2023 — when Galvez and US Ambassador MaryKay L. Carlson held a joint press conference at Camp Aguinaldo — the four new sites were publicly named: (1) Naval Base Camilo Osias in Sta. Ana, Cagayan, on the northeastern tip of Luzon facing the Bashi Channel and Taiwan; (2) Camp Melchor F. Dela Cruz in Gamu, Isabela, in northeastern Luzon; (3) Lal-lo Airport in Lal-lo, Cagayan, a few kilometres from Naval Base Camilo Osias; and (4) Balabac Island in Palawan, in the southwestern Philippines facing the Spratlys and the Sulu Sea. A fifth designation — Antonio Bautista Air Base in Puerto Princesa, Palawan — was added later in 2023; whether this brought the total to nine (with Bautista counted as new) or to five-plus-four (with Bautista counted as a recategorisation of an existing site) was reported inconsistently in 2023 coverage. The Department of National Defense's settled position by 2024 was that there are nine EDCA Agreed Locations.

The Austin–Galvez 2 February announcement was the inflection point. From this moment forward, the alliance pivot was public, irreversible without significant diplomatic cost, and operationally concrete.

3.3 The Five New Sites — Geography and Strategic Reading

The geographic logic of the new sites is bi-directional and, by 2024, openly acknowledged in US Congressional testimony as such. Three of the four new northern sites — Naval Base Camilo Osias, Lal-lo Airport, and Camp Melchor F. Dela Cruz — cluster in Cagayan and Isabela provinces in northeastern Luzon. The Bashi Channel separating northern Luzon from Taiwan is approximately 250 kilometres wide; a Taiwan Strait contingency would activate this maritime chokepoint. US Indo-Pacific Command testimony before Congress — Admiral John C. Aquilino in March 2023 and his successor Admiral Samuel J. Paparo in April 2024 — explicitly identified the value of "rotational access" in northern Luzon for "deterring contingencies in the first island chain."

Palawan, the home of the two southwestern sites (Balabac and, in the recategorised view, Antonio Bautista), is the Philippine province nearest the Spratly Islands. Balabac is approximately 200 kilometres east of the disputed Spratlys and dominates the southern approach to the South China Sea. Antonio Bautista Air Base in Puerto Princesa is the AFP Western Command (WESCOM) headquarters and the operational base for Philippine deployments to the Spratlys, including the BRP Sierra Madre resupply missions to Ayungin Shoal.

The strategic reading is unmistakable. Northern Luzon sites position the Philippines as a forward platform in any US response to a Taiwan Strait crisis. Palawan sites position the Philippines as a forward platform in any direct US engagement with Chinese forces in the South China Sea. Both functions were anticipated by US planning and welcomed by the Marcos Jr. administration on the calculation that capability presence at scale, on Philippine territory, generated the credible deterrence that a paper MDT commitment alone could not.

3.4 The Domestic Reception — Cagayan, Palawan, Local Government Pushback

The domestic reception was mixed and politically structured. Cagayan Governor Manuel N. Mamba — a Marcos ally on most matters and a member of the Lakas-CMD party — publicly opposed the designation of Naval Base Camilo Osias and Lal-lo Airport, characterising the move as importing US conflicts into his province and as inviting Chinese economic retaliation given the Chinese investment in Cagayan agriculture and infrastructure. Mamba travelled to Beijing in March 2023 to meet provincial Chinese officials; he was widely reported as having received assurances about continued Chinese investment if Cagayan's local government continued to resist the EDCA designation.

The Marcos administration's response was firm but accommodating in form. President Marcos personally hosted a meeting with northern Luzon governors and mayors at Malacañang on 19 April 2023, in which he reiterated that EDCA Agreed Locations remained Philippine facilities, that no permanent US basing was contemplated, and that local government concerns about economic and social impact would be addressed through a community-benefits package. The administration also commissioned an EDCA Implementation Coordinating Committee with local government representation. By mid-2023, Governor Mamba's public opposition had become muted; his eventual position settled into a posture of cooperation with conditions.

Palawan's local-government posture was different. Governor Victorino Dennis M. Socrates, like his predecessor José Ch. Alvarez, was broadly supportive. Palawan provincial leaders had directly experienced Chinese fishing-fleet incursions, harassment of Filipino fishermen, and the de facto exclusion of Filipino fishing from Scarborough Shoal since 2012; the alliance pivot enjoyed substantial local-government support in Palawan as a function of direct experience with the costs of the alternative.

The harder-left and pro-China-balancer critique came not from local governments but from former President Duterte, Vice-President Sara Duterte (in muted form, before the coalition rupture), the Bayan Muna parliamentary remnant, certain Catholic Bishops' Conference of the Philippines (CBCP) statements, and academic commentators including Walden Bello and Roland Simbulan. The principal critique held that EDCA expansion would draw the Philippines into a US-China war the Philippines could not control, would invite Chinese economic and possibly military retaliation, and would compromise the non-aligned tradition stretching back to the 1955 Bandung Conference and to Senator Claro M. Recto's "Filipino First" tradition. This critique remained active throughout 2023–2025 but did not translate into legislative or judicial obstruction.

4. The Washington Pivot — Biden, Bilateral Defense Guidelines, and the "Ironclad" Doctrine (May 2023)

4.1 The 1 May 2023 White House Visit and Joint Statement

President Marcos's 1 May 2023 White House visit was the first Philippine state-level visit to Washington since Benigno S. Aquino III in 2014. The visit was scheduled for late April–early May and was the Biden administration's most significant Indo-Pacific bilateral engagement of the year other than the 11 April 2024 trilateral with Japan. President Marcos was accompanied by First Lady Liza Araneta-Marcos, Defense Secretary Galvez, Foreign Secretary Manalo, Trade Secretary Alfredo E. Pascual, and a delegation including Senator Imee R. Marcos, Senate President Juan Miguel "Migz" Zubiri, Senator Bong Go, and a substantial business contingent.

The 1 May joint statement, issued by the White House, contained four operative commitments. First, the United States and the Philippines committed to a "shared vision" of an Indo-Pacific that is "free and open, connected, prosperous, secure, and resilient." Second, the United States reaffirmed the MDT and its commitment to mutual defence in the event of an "armed attack on the Philippine armed forces, public vessels, or aircraft — including those of its Coast Guard — anywhere in the South China Sea." Third, the parties committed to a Trilateral Cooperation framework with Japan. Fourth, the parties committed to a Strategic Bilateral Dialogue at the foreign secretary–secretary of state level and to forthcoming Bilateral Defense Guidelines.

The third commitment — the formal commitment to a Trilateral with Japan — was the diplomatic precursor to the 11 April 2024 Biden–Kishida–Marcos summit. The fourth — the Bilateral Defense Guidelines — would be produced within forty-eight hours (Section 4.2). The second — the "ironclad" extension of the MDT to coast guard vessels in the South China Sea — was the most important. It closed a doctrinal gap that had constrained Philippine confidence in the MDT since the 2012 Scarborough standoff, when the United States had famously declined to intervene to prevent Chinese seizure of the shoal because the contested feature was not an "island" under Philippine territorial baselines and the Philippine vessels involved were not Philippine Navy combatants.

4.2 The 3 May 2023 Bilateral Defense Guidelines — First Ever, Substance and Significance

The Bilateral Defense Guidelines (BDG), released by the US Department of Defense and the Philippine Department of National Defense on 3 May 2023 in a joint document, are unprecedented in the seven-decade history of the alliance. The document is approximately twelve pages in its public English text. Its preamble notes that the BDG "modernise" the MDT for the contemporary strategic environment and "operationalise" the commitments the parties have undertaken under the MDT, VFA, MLSA, and EDCA.

The BDG specifies, in operative paragraphs: (1) that the MDT applies to armed attacks "by any state actor" — language deliberately inclusive of Chinese coast guard and maritime militia vessels in addition to PLA Navy combatants; (2) that the MDT applies to attacks "anywhere in the Pacific, including the South China Sea, on any of the parties' public vessels, aircraft, or armed forces — including the Philippine Coast Guard"; (3) that "asymmetric, hybrid, and irregular warfare and grey-zone tactics" are recognised as in-scope challenges; (4) that the parties will pursue "combined planning and exercise activities" under a Joint Strategic Planning Construct; (5) that "interoperability and connectivity" will be enhanced through information sharing, secure communications, and combined logistics; and (6) that "the new domains of cyber and space" are recognised as theatres in which alliance commitments apply.

The document's substantive significance was understood by both governments to lie in the codification of what had previously been clarified piecewise. The 2019 Pompeo–Locsin Manila joint press conference statement (1 March 2019) — in which Secretary Pompeo first stated publicly that the MDT applied to attacks in the South China Sea — had been an oral clarification. The 2021 Austin–Lorenzana virtual exchange (during the 30 July 2021 visit, in conjunction with the VFA restoration) had reiterated the position. But neither was a written, jointly negotiated, formally published doctrinal document. The BDG was all three.

4.3 The "Ironclad" MDT Extension to the South China Sea

The "ironclad" formulation deserves separate treatment because it functions as the diplomatic shorthand for the BDG's commitment and because its construction was deliberate. Secretary Austin used the word "ironclad" in his 2 February 2023 Manila statements. Secretary Blinken used it during the 11 April 2023 2+2 ministerial dialogue. President Biden used it during the 1 May 2023 joint press appearance with Marcos. The repeated use was a deliberate alliance-management technique: the word imparts emotional weight, communicates resolve, and creates a public commitment whose retraction would carry political cost.

The substance the word references is the BDG's combined coverage paragraphs: the application of the MDT to armed attacks on Philippine armed forces, public vessels, aircraft, and Coast Guard, anywhere in the Pacific including the South China Sea, by any state actor. The "ironclad" language was repeated by every senior Biden administration official with Philippine portfolio responsibility through 2024 — Secretary Austin during the 18 March 2024 Manila visit and the 1 May 2024 Hawaii Squad meeting; Secretary Blinken during his January 2024 and March 2024 Manila visits; Indo-Pacific Coordinator Kurt M. Campbell in multiple speeches; INDOPACOM commanders Aquilino and Paparo before Congress. By 2024 the formulation had become standard Philippine and US diplomatic vocabulary, deployed at the level of routine statement.

4.4 The Strategic-Rebalance Lexicon and Its Construction

The 2023 pivot was accompanied by the construction of a new lexicon. Marcos administration officials began to characterise the policy not as "alliance" or "alignment" but as "strategic rebalance" — language designed to position the move as a sovereign Philippine recalibration toward a balance the Duterte period had distorted, rather than as a subordination to US strategic preferences. The lexical move was politically purposeful: it accommodated nationalist sensibilities, preserved the rhetorical option of further calibration in either direction, and inoculated against the critique that the Marcos administration was returning to a 1950s-style client-state posture.

The lexicon's elements included: "comprehensive strategic partnership" (to characterise the bilateral with the US), "rules-based international order" (to characterise the legal frame of the South China Sea contest), "independent foreign policy" (Article II, Section 7 of the 1987 Constitution; preserved as the doctrinal framing of Philippine sovereign choice), "convergent interests" (to characterise the basis of Squad cooperation), and "transparency initiative" (to characterise the PCG public-attribution strategy). The vocabulary's deliberate use — across DFA statements, NSC public communications, and Presidential statements — established a register within which the alliance expansion could be discussed without triggering the "puppet of America" critique that had dogged earlier alliance moves.

5. The Squad Architecture — US–Japan–Philippines–Australia Quadrilateral (2023–2025)

The "Squad" terminology entered Indo-Pacific security discourse in early 2024, used initially by US INDOPACOM staff and adopted by analysts to distinguish the US–Japan–Australia–Philippines quadrilateral from the established US–Japan–India–Australia "Quad." The Squad is younger, narrower in geographic focus (concentrated on the South China Sea theatre), and operationally tighter than the Quad. It also positions the Philippines as a strategic principal rather than as a peripheral partner.

5.1 The Trilateral Leaders' Summit at the White House (11 April 2024)

The 11 April 2024 trilateral summit between President Biden, Japanese Prime Minister Fumio Kishida, and President Marcos was the diplomatic centrepiece of the 2024 alliance year. Kishida's state visit to Washington — his first as Prime Minister — produced multiple bilateral US–Japan deliverables (the modernisation of US Forces Japan command, joint development of next-generation interceptors, the AUKUS Pillar II Japan consultations); the trilateral was scheduled to immediately follow.

The Trilateral Leaders' Joint Vision Statement issued on 11 April 2024 contained operative commitments in five areas. First, it characterised the three countries as "natural partners" in defence of the rules-based maritime order, with explicit reference to the 12 July 2016 arbitral award. Second, it announced an expansion of trilateral maritime cooperative activities (the first such MCA had occurred 7 June 2023 in the South China Sea). Third, it committed Japan to participation in the upgrading of the Philippines' Subic Bay Freeport — including potential dual-use facilities — and to financial support for the Philippines' maritime domain awareness (MDA) capability through Official Security Assistance grants. Fourth, it committed to a Trilateral Defense Ministerial mechanism. Fifth, it committed to a Trilateral Maritime Dialogue at senior official level.

The Japan dimension is significant beyond the immediate deliverables. Japan and the Philippines signed a Reciprocal Access Agreement (RAA) on 8 July 2024 in Manila — the first such agreement Japan had concluded with a Southeast Asian country. The RAA provides the legal framework for Japan Self-Defense Forces to deploy to the Philippines for exercises and operations and reciprocally; it is the Japanese-Philippine functional equivalent of the US-Philippine VFA. The 11 April 2024 trilateral provided the political-level cover for the RAA negotiation's conclusion.

5.2 The First Squad Defense Ministers' Meeting in Hawaii (May 2024)

The first Squad — US, Japan, Australia, Philippines — defense ministers' meeting was convened by US Secretary Austin at Joint Base Pearl Harbor–Hickam, Hawaii, on 2 May 2024. Australian Defence Minister Richard Marles, Japanese Minister of Defense Minoru Kihara, and Philippine Defense Secretary Gilberto C. Teodoro Jr. (who had succeeded Galvez in June 2023) attended. The four-way joint statement issued at the conclusion of the meeting was unprecedented: it characterised the South China Sea situation in unified language, reaffirmed the four countries' commitment to UNCLOS and the 2016 arbitral award, and announced a programme of multilateral maritime cooperative activities and combined exercises.

The strategic significance of the four-way statement lay in the unified line on the 2016 award. Japan and Australia, as third parties to the arbitration, had previously commented on the award only in broad terms; the 2 May 2024 statement positioned all three external parties — US, Japan, Australia — alongside the Philippines in characterising the award as final and binding under international law. This created a four-country diplomatic bloc on a question where Beijing had pursued bilateral isolation of Manila.

Subsequent Squad ministerial-level meetings followed. The second Squad ministers' meeting was convened on 18 November 2024 in Darwin, Australia, on the margins of the ASEAN Defense Ministers' Meeting-Plus (ADMM-Plus); the third was convened in Manila on [TBD-VERIFY: specific 2025 date] during the first half of 2025. The Tokyo iteration anticipated by the framework had not yet occurred as of the May 2026 corpus cut.

5.3 Tokyo, Manila, and the Maritime Cooperative Activities

The operational expression of the Squad and the Trilateral is the Maritime Cooperative Activity (MCA) — a coordinated multi-ship transit through the South China Sea in formation, with reciprocal-deck operations and combined drills. The first MCA between the US, Japan, and the Philippines occurred on 7 June 2023 in the West Philippine Sea, involving the Philippine Navy's BRP Gregorio del Pilar, the US Navy's USS Ralph Johnson, and the Japan Maritime Self-Defense Force's JS Izumo. The first four-way MCA — adding Australia — occurred on 7 April 2024 in the South China Sea.

By 2025, the MCA tempo had stabilised at approximately monthly four-way or three-way exercises. Each MCA produces a joint statement, public release of imagery, and a media note characterising the activity as in support of the rules-based maritime order. The MCAs are not joint patrols in the legal sense — Philippine constitutional and political constraints preclude that characterisation — but they are operationally equivalent in producing combined presence in contested water.

5.4 The Coast-Guard Quadrilateral and the Civilian-Layer Innovation

A distinctive feature of the 2023–2025 architecture is the elevation of coast-guard cooperation alongside navy cooperation. The Philippine Coast Guard (PCG) under Admiral Ronnie Gil L. Gavan, the US Coast Guard (USCG), the Japan Coast Guard (JCG), and the Australian Border Force (with the Royal Australian Navy supporting) have developed a quadrilateral coast-guard cooperation framework that operates parallel to the navy-led Squad.

The coast-guard layer is operationally important because the South China Sea contest is conducted principally by coast guards on both sides. The CCG, not the PLAN, is the lead Chinese instrument; the PCG, not the PN, is the lead Philippine instrument. Coast-guard cooperation produces capability-building (PCG vessels have received Japan Coast Guard training and US grants), tactical interoperability (joint exercises off Mariveles, Bataan, in mid-2024 included combined boarding and resupply drills), and political signalling (a coast guard quadrilateral statement is less escalatory than a navy quadrilateral one, while being functionally equivalent at the operational level).

The 1 June 2023 Japan grant of twelve coast-guard vessels to the Philippines (under a yen-loan facility worth approximately ¥51 billion) and the 16 March 2024 Japan-Philippines coast-guard joint exercise in Manila Bay are markers of the civilian-layer build-out. By 2025 the PCG had grown from a force of approximately 18,000 personnel in 2022 to approximately 25,000, with marked new acquisitions including the 97-metre multi-role response vessels BRP Teresa Magbanua and BRP Melchora Aquino (both Japan-built, 2022 commissioned).

6. The Second Thomas Shoal Crisis Cycle (2022–2025)

6.1 BRP Sierra Madre — The Grounded Sentinel and the Resupply Mission Architecture

The BRP Sierra Madre — formerly USS LST-821, then USS Harnett County, transferred to the Philippines as RPS Sierra Madre in 1976, redesignated BRP Sierra Madre in 1981 — was deliberately grounded by the Philippine Navy on Ayungin Shoal (Second Thomas Shoal in English; Ren'ai Jiao in Chinese) on 9 May 1999 during the Estrada administration. The grounding was a calculated act of sovereignty assertion in response to Chinese construction at Mischief Reef earlier in the 1990s. The hulk has remained on the shoal continuously since, manned by a small rotating detachment of Philippine Marines (typically eight to ten personnel).

Ayungin Shoal sits within the Philippine exclusive economic zone (under UNCLOS and the 2016 award) approximately 105 nautical miles from Palawan and is one of the closest contested features to the Philippine mainland. The 2016 arbitral award explicitly found that Ayungin is a low-tide elevation within the Philippine EEZ and continental shelf, that China has no lawful claim to it, and that China's interference with Philippine activities at Ayungin violates Philippine sovereign rights.

The resupply architecture has been continuous since 1999 but escalated in incident frequency from 2021 onward. Standard resupply runs use Philippine Coast Guard or contracted civilian vessels to deliver food, water, fuel, and rotating personnel from Palawan to the Sierra Madre. Earlier resupply missions had been completed without major incident; from approximately November 2021, the CCG began intervening with water-cannon, blocking manoeuvres, and harassment.

6.2 The 2023 Cycle — Water Cannon, Lasers, the Romualdez/Tarriela "Transparency" Strategy

The 2023 cycle produced four publicly documented incidents that established the pattern. On 6 February 2023 (Section 3.1 above), a CCG vessel deployed a green laser against BRP Malapascua, temporarily blinding crew. On 5 August 2023, a CCG vessel deployed water cannon against Philippine resupply boats Unaizah May 1 and Unaizah May 2 approximately 13 nautical miles from Ayungin, preventing the resupply mission's completion. On 10 November 2023, CCG vessels again deployed water cannon against PCG vessels BRP Cabra and BRP Sindangan, and a Chinese maritime militia vessel reportedly rammed BRP Cabra. On 9–10 December 2023, CCG vessels deployed water cannon against three Philippine resupply boats, damaging the Unaizah May 1 and a BRP Sindangan gunwale.

The Philippine response across the 2023 cycle developed under Ambassador Jose Manuel "Babe" G. Romualdez (the Philippine Ambassador to the United States) on the diplomatic side and under PCG Commodore Jay Tarriela on the operational-communications side. The "transparency strategy" — releasing video and photographic documentation of incidents within hours, hosting embedded journalists on resupply missions, and naming specific CCG hull numbers — became the principal Philippine instrument for imposing reputational cost on Chinese coercion. Tarriela's X account operated as the de facto real-time channel for incident attribution; major international wires (Reuters, AP, AFP, Bloomberg) reposted his documentation within their newsroom workflows.

The strategy generated four operational dividends. First, it supplied US, Japanese, and Australian governments with evidentiary material for joint statements that were issued promptly after each incident, creating a diplomatic rhythm of attribution. Second, it imposed financial and reputational cost on the People's Republic of China through international media coverage. Third, it built domestic Philippine public support for the alliance pivot — opinion polls (Stratbase ADRi, Pulse Asia, SWS) consistently showed 70%+ Philippine public approval for the trust-the-US and oppose-China-coercion positions through 2024. Fourth, it preserved Philippine credibility on the international rules-based-order line by demonstrating that the Philippines was operating within UNCLOS, not outside it.

6.3 The 17 June 2024 Boarding Incident — Most Violent Encounter

The 17 June 2024 incident at Ayungin Shoal was the most violent encounter between Chinese and Philippine forces in the 2022–2025 period and arguably the closest the alliance has come to MDT activation since 1951. The Philippine Navy was conducting a routine resupply mission to BRP Sierra Madre, using two RHIBs (rigid-hulled inflatable boats) operating from a larger vessel. CCG personnel — variously characterised as Coast Guard or maritime militia, the attribution disputed by Beijing — intercepted the RHIBs at close range using larger CCG inflatables.

According to the AFP press conference of 19 June 2024 and the subsequent video evidence released by the PCG and AFP, CCG personnel boarded the Philippine RHIBs, brandished bladed weapons (machetes, knives, and what appeared to be axes), punctured Philippine inflatable hulls, confiscated weapons and equipment, damaged communications gear, and seized cargo intended for the Sierra Madre. One Philippine Navy sailor, Seaman First Class Jeffrey Facundo, suffered the severance of his right thumb during the confrontation. He was evacuated to a military hospital and underwent surgical reattachment.

The 17 June incident triggered a sustained diplomatic response. President Marcos convened the National Security Council in emergency session on 19 June 2024. US Secretary of State Antony Blinken issued a statement that same day reaffirming the MDT and condemning the CCG actions. President Biden telephoned President Marcos. Japanese, Australian, French, Indian, UK, EU, and Korean foreign ministries issued statements within forty-eight hours. The G7 foreign ministers' communique of 26 June 2024 included a paragraph specifically on the incident. The Philippine Department of Foreign Affairs issued the strongest diplomatic protest of the cycle to the Chinese Embassy.

The principal strategic question raised by the 17 June incident was whether it constituted an "armed attack" within the meaning of the MDT. The Philippine and US governments, after consultation, characterised the incident publicly as falling short of armed attack — a calibrated judgement that preserved diplomatic space, avoided an immediate escalation cycle, and reserved the MDT instrument for a future incident of greater severity. Critics within the Philippine commentariat (including Senator Risa Hontiveros and Stratbase ADRi commentators) characterised the no-armed-attack determination as too cautious; alliance managers characterised it as wise.

6.4 The July 2024 Provisional Arrangement and Its Limits

In the weeks following the 17 June incident, intensive diplomatic exchanges between Manila and Beijing — channelled through the Philippine Foreign Affairs Department's Office of Asian and Pacific Affairs and the Chinese Vice Foreign Minister Sun Weidong — produced what was described as a "provisional arrangement" on resupply missions to BRP Sierra Madre. The arrangement was announced separately by Manila and Beijing on 21–22 July 2024, with significant divergence in characterisation.

The Philippine version, articulated by Foreign Secretary Manalo and Department of National Defense Spokesperson Arsenio Andolong, was that the arrangement allowed Philippine resupply missions to proceed "without prejudice" to the parties' respective positions on sovereignty and that the Philippines had not agreed to advance notification of resupply missions to Chinese authorities or to inspections of resupplied materiel. The Chinese version, articulated by Foreign Ministry spokespersons and the Chinese Embassy in Manila, was that the arrangement required Philippine prior notification of resupply missions to Chinese authorities and that resupplied materiel was limited to "humanitarian" supplies (food, water, medical supplies) and excluded construction materials that could reinforce the Sierra Madre hulk.

The divergent characterisations have remained unresolved through subsequent resupply missions. Operationally, the resupply tempo since July 2024 has been less confrontational — water cannons have been less frequently deployed; the boarding pattern of 17 June has not been repeated; resupply missions have proceeded — but the structural disagreement underlying the arrangement remains. The Philippine position is that the arrangement is a confidence-building measure that does not modify Philippine sovereign rights; the Chinese position is that it acknowledges Chinese jurisdiction over Ayungin's waters.

6.5 The 2024–2025 Resupply Tempo Under the New Modus

From August 2024 through 2025, the resupply tempo settled into a roughly monthly rhythm with reduced (but not eliminated) Chinese harassment. Significant incidents continued: a CCG water-cannon deployment in October 2024 near a Philippine resupply boat at Sabina Shoal (Section 7.2 below) signalled that the "provisional arrangement" was narrowly geographic in coverage. The deployment of construction materials to the Sierra Madre — confirmed in resupply manifests published by the AFP in late 2024 — drew Chinese protest but no operational obstruction.

By the close of 2025, the resupply architecture had achieved a contingent stability: missions proceed, harassment continues at lower intensity than mid-2024, the Sierra Madre remains manned, and the underlying sovereignty contest remains unresolved. The arrangement is one bad incident away from collapse and one diplomatic process away from formalisation; in 2026 it will likely continue to be both.

7. Scarborough, Sabina, Iroquois, Pag-asa — The Wider West Philippine Sea Theatre (2022–2025)

7.1 Scarborough Shoal — Buffer-Zone Markers and the BRP Datu Sanday Incident

Scarborough Shoal — known in the Philippines as Bajo de Masinloc or Panatag Shoal, in China as Huangyan Dao — has been under de facto Chinese control since the April–June 2012 standoff that ended with the Philippines' tactical withdrawal under US-brokered terms that China then did not honour. The feature is approximately 220 kilometres west of Zambales province in Luzon. Since 2012, CCG vessels have maintained continuous presence and have generally prevented Filipino fishing within the lagoon, though Filipino fishermen have continued to operate on the outer reaches.

The 2024 cycle at Scarborough included three escalation markers. First, on 22 February 2024, CCG vessels installed floating barriers (a "buffer zone") at the entrance to the Scarborough lagoon, preventing Filipino fishing vessel entry. The PCG cut the barriers in a publicised operation on 25 September 2023 (an earlier incident that established the precedent) and again in 2024. Second, on 30 April 2024, a CCG vessel rammed the BRP Datu Sanday, a Philippine Bureau of Fisheries and Aquatic Resources vessel, during a fisheries patrol; the vessel sustained damage and required emergency repairs at Subic. Third, in November 2024, China announced "baselines of the territorial sea adjacent to Huangyan Dao," asserting a maritime claim built on straight baselines around the feature — a formal legal escalation discussed in Section 8.4.

7.2 Sabina (Escoda) Shoal — The BRP Teresa Magbanua Standoff (April–September 2024)

Sabina Shoal — known in the Philippines as Escoda Shoal and in China as Xianbin Jiao — is approximately 75 nautical miles west of Palawan. From April 2024, the PCG deployed the BRP Teresa Magbanua — one of the new Japan-built multi-role response vessels — to maintain presence at Sabina, after Philippine maritime scientists detected what appeared to be early-stage Chinese reclamation activity (coral damage patterns and dredge presence). The deployment was framed as a maritime-domain-awareness mission and as a sovereignty-presence operation.

The CCG responded with a sustained harassment campaign through April–September 2024, including blocking manoeuvres, water-cannon deployments, and a 19 August 2024 collision between BRP Teresa Magbanua and CCG vessel 5205 in which both vessels sustained damage. The standoff ended in mid-September 2024 when the BRP Teresa Magbanua withdrew from Sabina, citing fuel and supply constraints and crew rotation requirements. The withdrawal was characterised by the PCG as routine; Chinese state media characterised it as a Chinese victory in expelling the Philippine vessel.

The Sabina standoff is significant for two reasons. First, it demonstrated the operational limits of the Philippine "transparency strategy" — sustained presence operations require logistic depth that the PCG, despite recent acquisitions, does not yet possess at scale. Second, it tested whether the 2016 arbitral award's findings could be operationalised as sovereignty assertion: Sabina is a low-tide elevation within the Philippine EEZ, and the BRP Teresa Magbanua's presence was a direct invocation of that legal status. The outcome was ambiguous: the Philippines did not concede the legal point, but it did concede the operational position.

7.3 Iroquois Reef, Whitsun Reef, and the Maritime Militia

Iroquois Reef and Whitsun Reef (and several adjoining features) are sites of recurrent Chinese maritime militia gatherings. The Whitsun Reef incident of March 2021 — when more than 220 Chinese maritime militia vessels assembled at Whitsun for an extended period — established the pattern. Throughout 2022–2025, the PCG and the AFP have continued to document Chinese maritime militia presence at Whitsun, Iroquois, Sabina, and other features, often at the level of dozens to hundreds of vessels.

The maritime militia — the People's Armed Forces Maritime Militia (PAFMM) — operates under nominal civilian registration but is integrated into the People's Liberation Army Navy command structure. Its function is to assert presence below the threshold that would trigger conventional military responses while complicating the attribution and legal characterisation of incidents. The PCG's 2022–2025 documentation campaign — including AIS (Automatic Identification System) tracking, satellite imagery, and direct overflight photography — has produced the most comprehensive open-source record of PAFMM operations to date.

7.4 Pag-asa (Thitu) Island and the KIG Patrol Architecture

Pag-asa Island (Thitu Island in English; Zhongye Dao in Chinese) is the second-largest naturally formed feature in the Spratlys and is administered by the Philippines as part of the Kalayaan Island Group (KIG), a Palawan municipality. Approximately 200 Filipino civilians and a small AFP detachment live on the island. The 2020 completion of a beaching ramp and the 2023 reinforcement of the runway have improved Philippine logistic access to Pag-asa.

The 2022–2025 period saw repeated Chinese flotilla incidents near Pag-asa, including in March 2023 when more than forty CCG and PAFMM vessels were observed within 4–8 nautical miles of the island. The AFP Western Command (WESCOM) at Antonio Bautista Air Base coordinates Pag-asa support and the KIG patrol architecture. Operation Patuloy ("continuing") is the standing AFP designation for routine KIG patrols.

In December 2024 and January 2025, the AFP conducted Operation Lumbas ("wave" or "ride the wave" in Cebuano), a series of patrols aimed at the maritime militia presence in the broader KIG. The operation's name and public framing positioned the AFP/PCG as actively asserting jurisdiction rather than passively responding to Chinese presence. The operation's operational results were modest — the maritime militia is not easily displaced by patrol presence — but its political-signalling value was significant.

8. The Legal Architecture — UNCLOS, the 2016 Award, and the 2024 Maritime Zones Acts

8.1 The 2016 Arbitral Award as Operational Doctrine, Not Just Diplomatic Talking Point

The 12 July 2016 Award in The Republic of the Philippines v. The People's Republic of China (PCA Case No. 2013-19) found, among other things: that there is no legal basis for China's "nine-dash line" historic-rights claim; that no feature in the Spratly Islands is a "naturally formed area of land surrounded by water" that generates an EEZ or continental shelf (i.e., none is an "island" under UNCLOS Article 121); that Scarborough Shoal generates only a territorial sea (not an EEZ); that several features within the Philippine EEZ are low-tide elevations or fully submerged features incapable of generating any maritime entitlement; and that China violated Philippine sovereign rights at multiple specific locations including Mischief Reef, Second Thomas Shoal, and Scarborough.

China refused to participate in the proceedings and rejects the award as "null and void." The Philippine position under the Aquino III, Duterte, and Marcos Jr. administrations has been formally that the award is binding under international law; the operational use of the award has varied. Under Aquino III (June 2016) the award was filed but the administration was ending; under Duterte (2016–2022) the award was de-emphasised in public diplomacy but never repudiated; under Marcos Jr. (2022–) the award has been actively invoked in diplomatic notes, in PCG and DFA public statements, in international forums (G7, ASEAN, UN), and in the 2024 Maritime Zones Act.

The shift from talking point to operational doctrine under Marcos Jr. has had concrete consequences. PCG public-attribution releases now routinely invoke the award's specific findings (e.g., that Sabina is a low-tide elevation within the Philippine EEZ); Philippine joint statements with the US, Japan, Australia, the UK, France, and the EU now include the award's binding status as a standard clause; the 2024 Maritime Zones Act translates the award's geographic findings into domestic Philippine statute (Section 8.2). The 2016 award has become not just a diplomatic resource but the operating legal framework for Philippine maritime claims.

8.2 The 8 November 2024 Philippine Maritime Zones Act (RA 12064)

President Marcos signed Republic Act No. 12064, the Philippine Maritime Zones Act, on 8 November 2024 at a ceremony at Malacañang attended by Senate President Francis "Chiz" Escudero, Speaker Martin G. Romualdez, Foreign Secretary Manalo, Defense Secretary Teodoro, and members of the Senate Foreign Relations Committee. The Act had passed the House of Representatives on 17 September 2024 and the Senate (in third reading) on 24 September 2024.

RA 12064 codifies the Philippine territorial sea (12 nautical miles), contiguous zone (24 nautical miles), exclusive economic zone (200 nautical miles), and extended continental shelf consistent with UNCLOS. The Act's text expressly references the 12 July 2016 arbitral award as binding upon the Philippines and the People's Republic of China, and as supplying the geographic specification of certain features and zones. The Act provides for criminal penalties for violations of Philippine maritime zones, including unauthorised resource exploitation and unauthorised military activity.

The notable significance of RA 12064 is threefold. First, it translates the 2016 award's geographic findings into domestic Philippine law, creating a domestic statutory basis (in addition to the international-law basis) for Philippine enforcement actions. Second, it provides a legal mechanism for the prosecution of foreign actors operating within Philippine maritime zones — Chinese fishing vessels, CCG personnel involved in incidents, and PAFMM operators have all theoretically become subject to Philippine criminal jurisdiction. Third, it sends a diplomatic signal that the 2016 award is permanent Philippine legal patrimony, not a discretionary diplomatic asset susceptible to administration-by-administration reinterpretation.

8.3 The Archipelagic Sea Lanes Act (RA 12065) and Its Operationalisation

Republic Act No. 12065, the Philippine Archipelagic Sea Lanes Act, was signed together with RA 12064 on 8 November 2024. It exercises the Philippines' right as an archipelagic state under UNCLOS Article 53 to designate sea lanes for international transit through the archipelago. The Act designates three sea lanes: a northern lane (through the Mindoro Strait and Sibutu Passage); a central lane (through the Visayan Sea and Sulu Sea); and a southern lane (through the Surigao Strait and southern approaches).

The Act's significance is dual. Constitutionally, it asserts archipelagic sovereignty by exercising a UNCLOS right the Philippines had not previously formalised. Strategically, it positions the Philippines to regulate transit through some of the most strategically important maritime chokepoints in the Indo-Pacific. The Surigao Strait, in particular, is a principal route for shipping between the Pacific and the South China Sea via the Philippine archipelago.

China's response — and the responses of other states — to the sea lanes designation has been measured. The United States, while broadly supportive of Philippine maritime claims, has historically maintained that excessive coastal-state regulation of transit can infringe on freedom of navigation; the US has not formally protested the sea lanes designation but has reserved its position. China's protest focused on the Maritime Zones Act rather than on the Archipelagic Sea Lanes Act specifically.

8.4 China's Scarborough Straight-Baseline Counter-Claim and the Lawfare Exchange

China's response to the 8 November 2024 Philippine legislation came in two forms. First, an immediate diplomatic protest delivered to the Philippine Embassy in Beijing on 8 November 2024, characterising both laws as "null and void" and reiterating Chinese sovereignty over the South China Sea features. Second — and more consequentially — China announced on 10 November 2024 the publication of "baselines of the territorial sea adjacent to Huangyan Dao," i.e., a straight-baseline declaration around Scarborough Shoal.

The straight-baseline declaration purported to convert Scarborough — which the 2016 arbitral award found to be a feature generating only a territorial sea — into a feature with broader claimed maritime entitlements. The declaration is inconsistent with the 2016 award and is, in the Philippine legal characterisation, "null and void on its face." The DFA filed a formal protest on 11 November 2024 and a series of follow-on protests at the UN and through bilateral channels.

The lawfare exchange of November 2024 illustrates that the legal contest is now bilateral and ongoing. Each side asserts maritime entitlements through domestic legislation or executive declaration; each side rejects the other's assertions; each side seeks third-party support for its position. The lawfare layer is not a substitute for the operational contest but an organising frame within which the operational contest is conducted.

The alliance expansion is not principally rhetorical or institutional; it is also material. Between 2023 and 2025, US capabilities deployed to or staged through the Philippines reached levels not seen since the 1991 base closures. Three deployments — the Typhon Mid-Range Capability, HIMARS rotations, and intelligence-sharing infrastructure — define the capability layer.

9.1 The Mid-Range Capability (Typhon) Deployment to Northern Luzon (April 2024)

The US Army Pacific deployed the Mid-Range Capability (MRC) system — also known by the developmental name "Typhon" — to northern Luzon in early April 2024 for the Salaknib 2024 and Balikatan 2024 exercises. The deployment arrived at Laoag International Airport in Ilocos Norte aboard a C-17 Globemaster on 7 April 2024 and was subsequently relocated to Camp Melchor F. Dela Cruz in Gamu, Isabela. The deployment was announced by the US Army Pacific on 15 April 2024 in a press release that characterised it as part of "exercise activities" — language that left ambiguous whether the system would be withdrawn at exercise conclusion.

The Typhon system fires the Tomahawk Land Attack Missile (TLAM-N), a long-range cruise missile with a range exceeding 1,500 kilometres, and the Standard Missile-6 (SM-6), which has anti-ship variants. From northern Luzon, Typhon's effective range covers major Chinese coastal target sets including Hainan Island's naval facilities, portions of the South China Sea contested features, and — in the longer-range Tomahawk configuration — continental Chinese targets. The deployment was the first ground-based, intermediate-range missile system stationed in the first island chain since the 1987 Intermediate-Range Nuclear Forces Treaty (which the US exited in August 2019).

China's response was sustained and at high level. Foreign Minister Wang Yi raised the Typhon deployment in multiple bilateral meetings with Philippine and US counterparts. Chinese state media characterised the deployment as a provocation creating a "new front" in regional tensions. China demanded the withdrawal of the system; the US and the Philippines declined.

The deployment's anticipated post-exercise withdrawal did not occur. The Typhon remained in northern Luzon through 2024 and into 2025. The 18 January 2025 announcement by the Philippine Department of National Defense — that the Typhon would remain in country "indefinitely" for "continued exercise and interoperability activities" — formalised what had been an ambiguous open-ended retention into a clear capability presence. By mid-2025, the strategic-significance of the Typhon retention had been widely identified as the dimension of the 2022–2025 expansion that most concretely altered regional capability balances.

9.2 HIMARS, Patriot, and the Capability Debate

Alongside the Typhon, additional US Army capabilities have been deployed on a rotational basis. The High-Mobility Artillery Rocket System (HIMARS) — a multiple-rocket-launch system with extended-range munitions — has been used in Balikatan and Salaknib exercises since 2023. The Patriot air defence system was deployed to the Philippines for Balikatan 2024 and again for Balikatan 2025. US Marine Corps NMESIS (Naval Marine Expeditionary Ship Interdiction System), an anti-ship missile system, was deployed for the first time during 2024 exercises and remained on rotational presence.

The Philippine domestic-political debate around the capability layer has focused on three questions. First, on the consent question: under what conditions can foreign-flagged military capability be deployed on Philippine soil without triggering the Article XVIII Section 25 constitutional requirement for Senate-ratified basing? The administration position is that rotational, time-bound deployments under existing VFA/EDCA frameworks do not constitute "basing" in the constitutional sense. Senator Imee Marcos and others have argued that indefinite retention shades into basing in fact if not in name.

Second, on the target question: does the deployment of capability with range to strike continental China constitute a defensive or offensive posture, and how does the answer affect the Philippines' obligations under its independent foreign policy? The administration argues the capabilities are deterrent and defensive in character; critics including Senator Hontiveros and Walden Bello argue that the targets implicate the Philippines in a US-China contest the Philippines is not positioned to manage.

Third, on the consequences question: does Chinese economic retaliation against the Philippines — through reduced agricultural imports, withdrawal of infrastructure investment, or supply-chain pressure — materially injure the Philippine economy in ways that exceed the strategic value of the capability presence? The administration argues that Chinese retaliation has been limited and that diversification of trade and investment partners has mitigated exposure. Critics argue that the data have not yet been generated to assess the full economic consequences.

9.3 The FY2024 NDAA $500 Million FMF Allocation

The US Congressional appropriations for Philippine Foreign Military Financing (FMF) scaled considerable across 2023–2025. The FY2024 National Defense Authorization Act, signed by President Biden on 22 December 2023, authorised approximately $500 million in FMF for the Philippines — the largest single-year FMF allocation to the Philippines since the immediate post-9/11 period. The actual appropriation followed in the FY2024 Department of Defense Appropriations Act and was disbursed across calendar 2024.

The $500 million FMF — supplemented by Excess Defense Articles (EDA) transfers including a former US Coast Guard cutter (now PCG BRP Melchora Aquino II, a different vessel from the Japan-built BRP Melchora Aquino), C-130 transport aircraft, and small-arms ammunition — has financed Philippine acquisitions of fast attack craft, maritime patrol aircraft, radar systems, and unmanned aerial vehicles. The acquisitions have flowed primarily to the Philippine Navy's Horizon 3 Modernisation Programme (covering 2023–2028) and to the PCG's vessel-expansion programme.

The FMF allocation is significant beyond its dollar figure. It establishes a precedent of large-scale US security assistance to the Philippines that future administrations — Philippine and US — will negotiate around. It creates a financial-flow dependency that has political consequences in both directions: Philippine modernisation has become meaningful dependent on US assistance, while US ability to manage Philippine alliance behaviour through assistance leverage has become material enhanced.

The most operationally consequential alliance investment may be in shared intelligence and maritime-domain-awareness infrastructure rather than in kinetic capability. The Philippine Coastal Hub — a maritime-domain-awareness fusion centre established under the Philippine Coast Guard with US, Japanese, and Australian technical assistance — entered operational use in 2024 at facilities co-located with WESCOM at Antonio Bautista Air Base in Puerto Princesa.

The Hub processes real-time AIS data, satellite imagery (from US National Reconnaissance Office shared feeds and from commercial providers including Maxar, Planet Labs, and BlackSky), and Philippine-collected maritime patrol data. The output supports PCG and AFP operational planning, supplies the public-attribution releases that fuel the transparency strategy, and feeds into joint intelligence assessments with US, Japanese, and Australian counterparts.

The 2024 announcement of a General Security of Military Information Agreement (GSOMIA) with Japan — signed alongside the Reciprocal Access Agreement on 8 July 2024 — provides the formal legal framework for sustained Japan-Philippines intelligence sharing. A parallel US-Philippines GSOMIA had been in effect since 2007. The intelligence-sharing layer is less visible than the Typhon deployment or the EDCA expansion but is plausibly more consequential for the day-to-day operational dynamics of the South China Sea contest.

10. Exercises — Balikatan, Salaknib, Kamandag, and the 2025 Scale (2023–2025)

10.1 Balikatan 2023, 2024, 2025 — The Scaling Curve

Balikatan ("shoulder-to-shoulder" in Tagalog) is the annual flagship US-Philippines joint exercise, conducted between the AFP and the US Indo-Pacific Command under the VFA framework. Its scale across 2023–2025 illustrates the alliance expansion concretely.

Balikatan 2023 (April 2023) involved approximately 12,200 personnel (5,400 Philippine, 6,800 US) — already the largest Balikatan since the exercise's modern revival. The 2023 edition introduced two notable innovations: live-fire sinking of a decommissioned Philippine Navy vessel (the BRP Pangasinan) by combined US-Philippine fires, and participation by Australian observers. The exercise involved sites across Luzon, Palawan, and Antique.

Balikatan 2024 (22 April – 10 May 2024) involved approximately 16,700 personnel (11,000 US, 5,000 Philippine, plus 250 Australian troops and observers from fourteen additional countries). The 2024 edition included multilateral maritime exercises in the Bashi Channel, a Batanes amphibious component (the northernmost Philippine province, directly facing Taiwan), the first live-fire deployment of HIMARS and Patriot, and the Typhon's initial deployment.

Balikatan 2025 (21 April – 9 May 2025) involved approximately 14,000 personnel (9,000 US, 5,000 Philippine) plus 260 Australian and 20 Japanese troops in observer-plus capacity. The 2025 edition included a full "defence of archipelago" scenario built around a hypothetical hostile incursion into Philippine maritime zones, Typhon participation, and reciprocal-deck operations with Japanese MSDF vessels.

The scaling curve — 5,000 in 2022 to 16,700 in 2024, with modest reduction to 14,000 in 2025 — reflects deliberate alliance design. The 2025 reduction was framed as a function of optimal-scale efficiency rather than retrenchment; the multilateral participation continued to expand even as the bilateral personnel count adjusted.

10.2 Salaknib, Kamandag, and the Specialist Exercises

Beyond Balikatan, the annual exercise rhythm includes Salaknib (army-to-army, US Army Pacific and Philippine Army), Kamandag ("Cooperation of Warriors of the Sea"; US Marine Corps and Philippine Marine Corps), Sama Sama (navy multilateral including Japan and other partners), and a variety of specialist exercises (Pacific Iron, Cope Thunder for air forces, MARFORPAC counterterrorism).

The 2024 Salaknib exercise (May 2024) included the Typhon's initial deployment and conducted live-fire artillery operations in the Crow Valley range in Tarlac. The 2024 Kamandag exercise (October 2024) included NMESIS anti-ship missile drills in the Babuyan Islands north of Luzon. The 2024 Sama Sama (October 2024) was the first explicitly multilateral iteration, with Japanese, Australian, Korean, French, UK, and Canadian naval participation.

The specialist exercises matter operationally because they build the granular interoperability — radio protocols, fire-control procedures, logistics interfaces, casualty-evacuation procedures — that determine whether the alliance's capability commitments are operationally meaningful or merely paper. The 2022–2025 expansion of the specialist exercise programme reflects deliberate alliance-design choice to invest in interoperability depth alongside top-line capability presence.

10.3 The Maritime Cooperative Activities — Trilateral and Quadrilateral Patrols

The Maritime Cooperative Activities (MCAs) — coordinated multi-ship transits through the South China Sea — constitute a third tier of operational presence alongside the bilateral Balikatan/Salaknib rhythm and the multilateral exercises. As noted in Section 5.3, the first US-Japan-Philippines MCA occurred on 7 June 2023 and the first four-way (adding Australia) on 7 April 2024.

By 2025, the MCA tempo had stabilised at approximately monthly events. Each MCA produces a joint statement, public imagery, and a media note. The MCAs are technically not "joint patrols" — a term constitutionally and politically contested in the Philippines — but they are operationally indistinguishable from patrols in their presence-projection function.

10.4 Operation Lumbas and Operation Patuloy — Internal PH Operations

Distinct from the bilateral and multilateral exercises, the AFP and PCG have conducted intensified unilateral operations in the West Philippine Sea since 2023. Operation Patuloy ("continuing") is the standing designation for routine KIG patrols. Operation Lumbas — initiated in late 2024 — targeted the Chinese maritime militia presence at Whitsun, Iroquois, and Sabina. Operation Bantay Karagatan (Sea Watch) operates as the umbrella maritime-domain-awareness operation across the West Philippine Sea.

The unilateral operations matter because they preserve the Philippine narrative that the alliance is supporting Philippine sovereign capability rather than substituting for it. PCG and AFP commanders consistently characterise alliance support as enabling rather than directing Philippine operations; the political resilience of the alliance pivot depends on this narrative remaining credible.

11. The Trump-2 Transition — Hegseth, Tariffs, and Alliance Stress-Test (November 2024 – May 2025)

11.1 The Marcos–Trump February 2025 Phone Call and the MDT Reaffirmation

Donald J. Trump's victory in the 5 November 2024 US presidential election introduced an immediate question into the Philippine alliance posture. The first Trump administration (2017–2021) had handled the alliance through Defense Secretary James Mattis's MDT clarifications (2018) and Secretary Pompeo's 2019 South China Sea statement, but Trump's personal posture had been transactional and unpredictable. The Marcos administration's pre-inauguration response was characterised by careful signalling: congratulatory message on 6 November 2024, working-level outreach through US embassy and Philippine embassy channels, and public messaging emphasising the durability of treaty-based commitments.

The first Marcos–Trump phone call occurred on 31 January 2025, eleven days after Trump's inauguration. The Philippine read-out characterised the call as "warm" and "productive"; the White House read-out reaffirmed the MDT and characterised the Philippines as a "critical ally" in the Indo-Pacific. Neither read-out mentioned tariffs.

The MDT reaffirmation by the Trump administration was marked important: it confirmed continuity at the treaty level despite the change in administration. The continuity reflected the institutional depth of the alliance — Defense Department, State Department, and INDOPACOM working-level positions that supported the existing alliance design persisted through the transition — but also reflected Trump's calculation that the Philippines was a useful asset in his China-pressure framing.

11.2 The Hegseth Manila Visit (28 March 2025) and Continuity Signalling

US Defense Secretary Pete Hegseth's first Southeast Asia visit included Manila on 28 March 2025. Hegseth met President Marcos at Malacañang and Defense Secretary Gilberto Teodoro at Camp Aguinaldo. The joint statement issued after the meetings reaffirmed the MDT, confirmed continuity of EDCA implementation, and announced the deployment of additional US capabilities to the Philippines including additional NMESIS units, expanded MQ-9B Sea Guardian unmanned reconnaissance assets, and continued Typhon presence.

The Hegseth visit was significant continuity-signalling. The notable announcements — additional capability, continued exercise rhythm, sustained intelligence sharing — were consistent with what a continuing Biden administration would have delivered. The political message was that the Trump-2 administration would not reverse the 2022–2024 alliance expansion in defence terms.

11.3 The 2 April "Liberation Day" Tariffs and the 17 Per Cent Philippine Exposure

Five days after the Hegseth visit, on 2 April 2025, President Trump announced "Liberation Day" reciprocal tariffs across US trading partners. The Philippines was assigned a 17 per cent reciprocal tariff. The United States is the Philippines' second-largest export destination (approximately 16 per cent of total Philippine exports, by 2024 figures); the tariff exposure was significant.

The Philippine response was calibrated. Trade Secretary Cristina A. Roque and Special Assistant for Investment and Economic Affairs Frederick D. Go led the bilateral trade negotiations. The Philippines did not retaliate; it pursued accommodation. The 90-day pause announced by Trump on 9 April 2025 created negotiation space. By mid-2025, partial accommodations were being negotiated — including potential carve-outs for semiconductor packaging exports — but the structural tariff exposure persisted.

The tariff episode established that the Trump-2 alliance management would be transactional in economic dimension even where it remained continuous in security dimension. The Philippines confronted a divide between security cooperation, which is firm, and economic cooperation, which is contestable. The medium-term sustainability of the alliance pivot now depends on whether economic-frictions cumulate to the point where they constrain security cooperation, or whether the two dimensions remain compartmentalised.

11.4 Alliance Dynamics Under Transactional Diplomacy

The transactional approach to alliance management has structural implications. Under the Biden administration, US alliance posture rested on shared-values and shared-system framings; under the Trump-2 administration, it rests on instrumental calculations of mutual benefit. The shift creates three operational consequences.

First, alliance commitments become more dependent on continuous demonstration of mutual benefit; "alliance maintenance" becomes a more active and contested process rather than an automatic continuation. Second, alliance leverage becomes more usable in both directions — the US can press for specific Philippine actions (e.g., basing access, public statements) in exchange for capability or trade concessions, and the Philippines can press for specific US actions (e.g., FMF allocations, MDT statements, deterrent deployments) in exchange for access or cooperation. Third, alliance public legitimacy in both countries becomes more dependent on visible immediate returns rather than on long-term strategic vision.

The Marcos administration's response to transactional alliance management has emphasised the value proposition: Philippine geography, Philippine treaty status, and Philippine willingness to permit forward presence are positioned as concrete US strategic assets that justify continued US investment in alliance capability and FMF flow. Whether this framing satisfies a Trump-2 alliance calculus over three additional years (through January 2029) remains an open question.

12. ASEAN, the COC, and the Regional Context

12.1 ASEAN's Code of Conduct Negotiations — Two Decades of Stagnation

The Code of Conduct (COC) for the South China Sea — anticipated by the 2002 ASEAN-China Declaration on the Conduct of Parties — has been under intermittent negotiation for over two decades. The Single Draft Negotiating Text (SDNT), first agreed in 2018, was intended to provide the working framework. As of mid-2025, the COC has progressed through approximately three reading-rounds but remains unfinalised on core questions: legal binding force, geographic scope, third-party-rights treatment, dispute-resolution mechanisms, and force-majeure provisions.

The Philippines' position on the COC has been calibrated. Under Duterte (2016–2022) the Philippines was relatively accommodative; under Marcos Jr. (2022–) the Philippines has insisted on three minimum conditions: COC must not undermine the 2016 arbitral award; COC must be legally binding; COC must not exclude or constrain third-party-state activities (i.e., US naval transits, joint exercises) in the South China Sea.

12.2 The April 2025 ASEAN-China COC Text Revisions

The April 2025 ASEAN-China senior officials' meetings produced revised draft text on several COC sections. The revisions, reported in Reuters and the Manila Bulletin, included compromise language on the third-party-rights question that the Philippines characterised as "improved" but not yet satisfactory. The Philippines, the US, and Japan continued to argue against any COC formulation that would constrain third-party state activities or freedom of navigation.

The COC's negotiation trajectory remains uncertain. The 2026 target for completion announced by Chinese Foreign Minister Wang Yi at multiple ASEAN meetings is widely characterised as aspirational rather than realistic. The Philippines' position is that a sub-optimal COC is worse than no COC, and that the absence of a finalised COC does not constrain the operation of UNCLOS and the 2016 award as binding instruments.

12.3 Indonesia, Vietnam, Malaysia — Differential Positions

The ASEAN claimant states diverge in their South China Sea postures. Indonesia, while not formally a claimant in the Spratlys, maintains a North Natuna Sea claim and has had its own water-cannon incidents with Chinese vessels; under President Prabowo Subianto (October 2024–), Indonesia has shown limited willingness to coordinate publicly with the Philippines but maintains its own enforcement operations.

Vietnam, the second-largest Spratly claimant after China, conducts its own land-reclamation programme (its features have expanded considerable in 2022–2024 satellite imagery analysed by AMTI) but coordinates with the Philippines selectively. Vietnamese maritime officials and Philippine counterparts have held quiet coordination meetings; public alignment is minimal.

Malaysia under Prime Minister Anwar Ibrahim has pursued a quiet-bilateral approach with China while maintaining its own claims; Malaysia's public posture has been notably less confrontational than the Philippine posture. The differential positions illustrate that the Philippines' transparency strategy and alliance pivot are not the ASEAN-default position; they are a distinctive Philippine choice that other claimants have, so far, declined to follow.

12.4 Japan, Korea, and the Indo-Pacific Coalition Layer

Beyond ASEAN, the Indo-Pacific coalition layer has developed meaningful. Japan's deepened engagement is detailed in Section 5. Korea's engagement has been incremental: the Yoon Suk Yeol administration (2022–) deepened bilateral defence cooperation with the Philippines, including a 9 October 2023 ROK Navy port call at Manila and participation in Sama Sama 2024. France has conducted FONOPs (Freedom of Navigation Operations) in the South China Sea and participated in MCAs; the UK's Carrier Strike Group operations included South China Sea transits in 2021 and 2025. India's participation has been limited but growing (the 2023 Manila visit by Indian Defence Minister Rajnath Singh signalled willingness to expand).

The Indo-Pacific coalition layer's significance for the Philippines is that it diversifies the alliance ecosystem beyond the US-bilateral. A Philippine alliance posture that rested exclusively on the US bilateral would be vulnerable to changes in US administration politics; the coalition layer creates redundancy and political legitimation.

13. Three-Account Reading — Administration, Critic, Structural

Following the three-account discipline established for contested topics, this section presents three parallel readings of the 2022–2025 alliance expansion without arbitrating among them.

13.1 The Marcos Administration Account — Restoration of Sovereignty

The administration account holds that the 2022–2025 expansion is the restoration of an independent foreign policy capable of defending Philippine territorial integrity and sovereign rights, after a six-year Duterte-era distortion. The 2016 arbitral award is invoked as the legal foundation of Philippine maritime claims, which the United States and its allies are bound to respect and assist in defending under the rules-based international order. EDCA expansion is characterised as the prudent acceptance of allied support — analogous to NATO members' acceptance of US deployments in Europe — to deter coercion by a numerically and capability-superior adversary. The Typhon and HIMARS deployments are characterised as defensive in character, applied to capabilities and contingencies the Philippines could not produce independently within a generational timeframe.

This account characterises the 2024–2025 South China Sea incidents not as evidence of failure but as evidence that the prior posture (Duterte-era accommodation) had not produced equilibrium — that Chinese coercion continued without reciprocal accommodation, and that the alliance pivot was the rational Philippine response. The 17 June 2024 boarding incident, on this account, is evidence not of alliance escalation but of Chinese choice; the July 2024 provisional arrangement is evidence that Philippine resilience can produce diplomatic adjustment.

13.2 The Pro-China-Balancer Critique — Sara Duterte, the PDP-Laban Position, the Non-Aligned Tradition

The critic account, articulated in varying registers by former President Duterte (until March 2025), Vice-President Sara Duterte, the PDP-Laban congressional bloc, certain CBCP statements, and academic commentators including Walden Bello, Roland Simbulan, and elements of the Bayan Muna remnant, holds that the alliance expansion has imported US strategic conflicts onto Philippine territory and has positioned the Philippines as a forward platform in a US-China rivalry the Philippines cannot influence and would suffer catastrophically from.

This account characterises the 2024–2025 incidents not as evidence of vindicated alliance positioning but as evidence that the alliance pivot has provoked Chinese response. On this account, the 2012–2022 period of relatively limited direct incidents (despite Duterte-era hedging) suggests that operational restraint had stabilising properties; the 2023–2025 escalation in incident frequency and severity is at least in part a function of the alliance pivot.

The non-aligned tradition is invoked: the 1955 Bandung Conference; Senator Claro M. Recto's "Filipino First" advocacy; the 1991 Senate rejection of the bases extension. On this reading, the Philippines' constitutional commitment to an "independent foreign policy" (Article II Section 7) is incompatible with the kind of forward-deployment-platform role the 2022–2025 expansion entails.

This account does not dispute that Chinese coercion is occurring; it disputes that the alliance pivot is the optimal Philippine response.

13.3 The Structural Reading — Chokepoints, Semiconductors, Island-Building, and the Long Game

The structural reading, drawing on geopolitical-economic frameworks including those advanced by Jay Batongbacal, Aileen Baviera (until her 2024 death), Renato Cruz De Castro, Richard Heydarian, and outside observers including Gregory Poling at CSIS, situates the 2022–2025 expansion within longer-term structural dynamics that pre-date and exceed the Marcos administration's choices.

Three structural features dominate this reading. First, the San Bernardino–Surigao Strait geography: the Philippine archipelago straddles the most important maritime chokepoints connecting the Pacific to the South China Sea. Whatever the political preferences of any Philippine administration, the archipelago's geographic position guarantees that any US-China contest will involve Philippine waters. Second, the semiconductor-supply-chain dimension: Taiwan's TSMC and the broader East Asian semiconductor architecture place strategic-economic interests at risk from any Taiwan Strait contingency, in ways that have increased material since 2020. Third, Chinese island-building: the 2014–2017 Chinese reclamation in the Spratlys (now stabilised at approximately 3,200 acres of new land across seven features, with airfields and military installations on Fiery Cross, Mischief, and Subi Reefs) is a permanent strategic-environment alteration that no diplomatic process can undo.

On this reading, the 2022–2025 alliance expansion is neither vindicated nor refuted by the events of 2023–2025; it is one Philippine response to structural conditions that would constrain any Philippine administration. The structural reading is broadly compatible with the administration account but emphasises that the structural conditions persist whether or not the alliance pivot succeeds in deterring Chinese coercion. Different administrations might pursue different tactical postures, but the strategic environment within which they choose is determined by geography, by industrial concentration, and by prior Chinese choices.

The structural reading also identifies the limits of any Philippine response. The Philippines cannot independently produce capabilities at scale that match the People's Liberation Army Navy; cannot independently sustain an alliance architecture against US-administration shifts; cannot independently determine the trajectory of the Taiwan Strait contingency. What it can do — under any administration — is structure its position to maximise leverage and minimise catastrophic exposure. The 2022–2025 alliance expansion represents one such structuring; the Duterte-era hedge represented another; the post-1991 bases-free reconstruction represented a third.

14. Forward View — Trajectories Into 2026 and Beyond

14.1 The Capability Trajectory — From Typhon to Indigenous Production

The capability trajectory through 2030 turns on three sub-questions. First, whether the Typhon deployment becomes a permanent rotational fixture or is withdrawn. The 18 January 2025 announcement of indefinite retention suggests permanence; a future Trump-2 decision could reverse this. Second, whether indigenous Philippine capabilities — radar, fast attack craft, drones, missile defence — scale to a level that meaningfully offsets the capability asymmetry. The Horizon 3 Modernisation Programme (2023–2028) is the formal AFP planning instrument; its execution depends on continued FMF flow and on Philippine budget sustainability. Third, whether emerging-technology dimensions — cyber, space, AI-enabled ISR — alter the calculation in ways that favour or disfavour the alliance posture. The 2023 Bilateral Defense Guidelines specifically anticipated these domains; their operational treatment is still being worked out.

14.2 The Crisis-Cycle Trajectory — Will Escalation Plateau or Spiral?

The 17 June 2024 incident represented a sharp escalation from the 2023 baseline; the July 2024 provisional arrangement appears to have produced a partial de-escalation. Two scenarios are plausible for 2026–2028. The first: a continued provisional-arrangement-stabilised resupply pattern, with incidents occurring at a frequency that the alliance and the Philippine PCG can manage without crossing the armed-attack threshold, and with diplomatic processes preserving negotiation space. The second: a more violent incident — for example, a CCG ramming with loss of Philippine life, a Chinese seizure of a Philippine vessel, or an incident at a more politically sensitive feature like Pag-asa — that triggers MDT consultation and a more escalatory cycle.

The probability of each scenario depends on factors not fully under Philippine or US control: the Chinese leadership's calibration of acceptable risk; Beijing's domestic political pressures; the Taiwan Strait contingency dynamics; the operational reliability of Chinese gray-zone instruments versus PLAN combatants.

14.3 The Domestic-Politics Trajectory — Alliance Through 2028

The 2028 Philippine presidential election will produce a constitutionally mandated successor to Marcos Jr. (single-term limit under Article VII Section 4 of the 1987 Constitution). The succession's identity will shape the alliance trajectory. Vice-President Sara Duterte — if the 2025 Senate impeachment trial does not convict her — remains in the constitutional line of succession through 2028 but is procedurally barred from the presidency only if convicted and removed. Whether she runs in 2028, and whether she runs on a continuity or rupture platform vis-à-vis the alliance, are open questions.

Other plausible 2028 candidates — Senator Bong Go, Senator Imee Marcos, Senator Manny Pacquiao (if his 2025 senatorial result holds), Vice-Presidential-quality candidates from the Hugpong and PDP-Laban alliances, and possibly outside candidates including Isko Moreno or successful regional governors — would each carry distinct postures toward the alliance. The Marcos administration's 2022–2025 alliance expansion would be more durable if a continuity successor is elected; it would be reversible (within constraints) if a rupture successor is elected.

14.4 Spiral Index — Cross-References to Companion Documents

The 2022–2025 alliance expansion does not stand alone; it is embedded in companion processes treated in detail elsewhere in the corpus. The reader is directed to:

PH-F-01 (1898–2024 baseline) for the deep-historical alliance arc and the legal architecture of MDT/VFA/MLSA/EDCA.
PH-F-02 (2016 South China Sea Arbitration and its Politics) [forthcoming] for the legal anchor of the arbitral award.
PH-D-03 (Marcos Jr. 2022 Election and Restoration) for the coalition-origin and electoral-mandate context.
PH-D-04 (Marcos–Duterte Coalition Rupture) for the institutional-mechanics of the domestic political fracture concurrent with the alliance pivot.
PH-D-05 (2025 Midterm Election and Impeachment Saga) for the 2024–2026 domestic-political frame and the Senate's role in alliance ratification.
PH-K-05 (2016 SCS Arbitration Decision) [forthcoming] for the decision-anchor companion to the legal architecture treated here.
PH-J-06 (Sara Duterte Impeachment Proceedings) [forthcoming] for the Vice-President's contested constitutional position concurrent with the alliance pivot.

The 2022–2025 expansion will, on present trajectories, be one of the defining features of the Philippine governance record of the 2020s. Whether it consolidates as durable strategic architecture or proves a high-water mark followed by partial recession depends on choices not yet made — by the Marcos administration's successors, by Chinese leadership, by US administrations through 2028 and beyond, and by the operational events of the South China Sea contest in 2026–2030. The document's task is to record what was decided, by whom, on what evidence, with what consequences, and within what contestation — so that future readers can assess the choices on the evidence the present supplies.

Sources

United States Department of State and Department of Defense. Joint Statement of the United States–Philippines 2+2 Ministerial Dialogue, Manila, 11 April 2023; and subsequent 2+2 communiqués, 2024 and 2025.
United States Department of Defense. Bilateral Defense Guidelines between the United States Department of Defense and the Philippines Department of National Defense, Washington, D.C., 3 May 2023.
The White House. Joint Statement of President Joseph R. Biden, Jr. and President Ferdinand R. Marcos, Jr., Washington, D.C., 1 May 2023; and Trilateral Leaders' Joint Vision Statement of the United States, Japan, and the Philippines, Washington, D.C., 11 April 2024.
Department of National Defense (Philippines). Press Statements and Briefings on the Expansion of the Enhanced Defense Cooperation Agreement and Designation of Four Additional Agreed Locations, 2 February 2023; and Annual Reports of the Philippine Department of National Defense, 2022, 2023, 2024, 2025.
Office of the Press Secretary / Presidential Communications Office (Philippines). Statements of President Ferdinand R. Marcos Jr. on the South China Sea, EDCA, and Alliance Affairs, 2022–2025; and First, Second, Third, and Fourth State of the Nation Addresses (25 July 2022; 24 July 2023; 22 July 2024; 28 July 2025).
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Philippine Coast Guard. Press Releases and Public Communications on West Philippine Sea Incidents (Second Thomas / Ayungin Shoal, Scarborough / Bajo de Masinloc, Iroquois Reef, Sabina / Escoda Shoal, Pag-asa / Thitu), 2022–2025; including statements by Commodore Jay Tarriela (PCG Spokesperson for the West Philippine Sea) and Admiral Ronnie Gil L. Gavan (PCG Commandant).
National Task Force for the West Philippine Sea (NTF-WPS) (Philippines). Press Briefings and Statements, 2022–2025; and Speeches of National Security Adviser Eduardo M. Año, 2023–2025.
Armed Forces of the Philippines (AFP). Statements on Balikatan 2023, 2024, and 2025; on Salaknib; on Kamandag; and on Operation Lumbas (Western Command, AFP), 2023–2025.
Center for Strategic and International Studies (CSIS), Asia Maritime Transparency Initiative (AMTI). Monthly West Philippine Sea Trackers, Satellite Imagery Reports, and Analytical Briefs, 2022–2025. Including briefs by Gregory B. Poling, Andreyka Natalegawa, and Harrison Prétat.
Batongbacal, Jay L. Selected commentary and journal articles, 2022–2025; including University of the Philippines Institute for Maritime Affairs and Law of the Sea (UP-IMLOS) Working Papers.
Stratbase ADR Institute (Manila). Pilipinas Conference 2023, 2024, 2025 Proceedings; and Stratbase ADRi Issue Briefs on the Indo-Pacific and the West Philippine Sea, 2023–2025. Including commentary by Dindo Manhit, Renato Cruz De Castro, and Victor Andres "Dindo" Manhit.
Council on Foreign Relations. Reports on US–Philippines Relations and the Indo-Pacific, 2022–2025. Including briefs by Sheila A. Smith and Joshua Kurlantzick.
Asia Foundation. State of Conflict and Violence in Asia: Philippines Country Update, 2023–2025.
Senate of the Philippines. Senate Foreign Relations Committee Hearings on the Visiting Forces Agreement, the Mutual Defense Treaty, and EDCA Implementation, 2022–2025; and Senate Resolutions relating to the South China Sea.
United States Senate Armed Services Committee and United States House Armed Services Committee. Testimony of US Indo-Pacific Commanders (Admiral John C. Aquilino; Admiral Samuel J. Paparo) on US Indo-Pacific Command Posture, March 2023, March 2024, April 2025.
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PH-H-PRES-03: Ferdinand Romualdez Marcos Jr. — "Bongbong" (1957–)
PH-F-01: The US–Philippines Strategic Relationship (1898–2024) — long-arc baseline; this document is the 2022–2025 zoom-in
PH-F-02: 2016 South China Sea Arbitration and its Politics — legal anchor of the West Philippine Sea position [forthcoming]
PH-K-05: The 2016 Filing of the South China Sea Arbitration — decision anchor [forthcoming]
PH-D-02: The War on Drugs — Numbers, Mechanics, ICC Investigation — Duterte-era institutional context
PH-D-03: The 2022 Election and the Marcos Family Restoration — coalition origin of the foreign-policy pivot
PH-D-04: The Marcos–Duterte Coalition Rupture (2024–2025) — domestic-politics context of the alliance pivot
PH-D-05: The 2025 Midterm Election, the Marcos–Duterte Rupture, and the Sara Duterte Impeachment Saga — concurrent domestic-political frame
PH-B-05: EDSA Revolution (22–25 February 1986) — origin of the post-bases constitutional architecture
PH-C-01: Corazon Aquino's Restoration Presidency (1986–1992) — the 1991 Senate vote anchor
PH-C-02: Fidel V. Ramos and the "Philippines 2000" Programme — VFA negotiation antecedent
PH-C-03: Estrada's Presidency and EDSA-Dos (1998–2001) — 1999 VFA ratification context
PH-D-01: Noynoy Aquino's Presidency (2010–2016) — 2014 EDCA signing context
PH-A-01: From Revolution to Commonwealth (1898–1935) — colonial foundation of the alliance architecture
PH-R-01: Philippines Governance Books Canon — source-canon anchor
PH-F-05: philippines japan reciprocal access agreement and the trilateral with us 2022 2026
MY-F-04: malaysia asean chairmanship 2025 and the anwar foreign policy doctrine
PH-D-06: Senate impeachment trial of VP Sara Duterte 2025-2026
PH-D-07: Philippines post-impeachment polity reset + 2028 pre-campaign 2025-2026
MY-D-07: back-reference added by symmetry sweep
PH-B-01: back-reference added by symmetry sweep
PH-F-06: The West Philippine Sea Confrontation and the "Assertive Transparency" Doctrine
PH-H-PRES-05: back-reference added by symmetry sweep
PH-K-06: The March 2025 Duterte ICC Arrest Decision
PH-K-07: The January 2013 Philippines–China PCA Arbitration Filing Decision
PH-H-PRES-06: Fidel Valdez Ramos — A Biography
PH-N-01: The Philippines in International Perceptions — People-Power Icon and Frontline State
PH-G-01: The Labour-Export State — OFW Policy Architecture (1974–2026) — OFW diplomacy and the labour corridors as the alliance frame's civilian counterpart
PH-O-01: Philippines Megatrends — The 2030s Questions