PH-F-01: The US–Philippines Strategic Relationship: From Colonial Inheritance to the EDCA Era (1898–2024)

1. Key Takeaways

• The relationship began as conquest, not compact. The 1898 Treaty of Paris transferred the Philippines from Spain to the United States for $20 million — a transaction in which Filipinos had no voice. The Philippine-American War (1899–1902) that followed this dispossession cost an estimated 200,000 Filipino civilian lives (TBD-VERIFY) and 4,200 American lives, establishing the asymmetry of power that has structured every subsequent arrangement. The bilateral relationship cannot be understood outside this foundational violence, which the formal treaty architecture of the post-independence period was designed, in part, to normalise and obscure.

• Independence in 1946 did not dissolve the structural dependencies created under colonialism. The Bell Trade Act of 1946, extracted as a condition of independence, gave American businesses parity rights in the Philippine economy through 1974. The 1947 Military Bases Agreement, signed the same year, placed 23 US military installations on Philippine soil — including Clark Air Base and Subic Bay Naval Station — on 99-year leases, creating a sovereignty compromise that Philippine nationalists never accepted as legitimate. The post-independence settlement preserved the economic and strategic infrastructure of colonial control while transferring formal sovereignty.

• The 1951 Mutual Defence Treaty remains the bedrock legal instrument, but its operational meaning has always been contested. The MDT commits both parties to act against "armed attack" on either party's metropolitan territory, Pacific island territories, or "island territories in the Pacific under their jurisdiction." Whether the South China Sea features that the Philippines claims — Scarborough Shoal, the Spratlys — fall under MDT protection was deliberately left ambiguous at signing and remained so until the 2023 Biden-Marcos joint statement explicitly extended the commitment to Philippine armed forces, coast guard vessels, and aircraft in the South China Sea.

• Washington's Cold War priorities produced a sustained tolerance for Philippine authoritarianism that delegitimised the alliance domestically. US support for Ferdinand Marcos through martial law (1972–1986) — channelling aid, hosting Marcos at the White House, suppressing criticism of human rights abuses — was driven by the strategic calculus that Clark and Subic were indispensable Cold War assets. When the Reagan administration finally withdrew support for Marcos during EDSA in February 1986, the signal came too late to repair the reputational damage: the alliance had been visibly complicit in fourteen years of dictatorship. This legacy structured Philippine ambivalence toward the US for decades.

• The 1991 Philippine Senate vote to reject the bases treaty was a decisive expression of sovereign will that restructured the alliance's legal basis permanently. The 12–11 Senate vote on 16 September 1991 against ratifying a new bases treaty — by a single vote — forced the closure of Clark Air Base (already destroyed by Mount Pinatubo's June 1991 eruption) and Subic Bay Naval Base by November 1992. The constitutional requirement in Article XVIII Section 25 of the 1987 EDSA Constitution — that foreign military bases require Senate ratification — was the procedural mechanism through which Philippine national sovereignty was exercised. The subsequent Visiting Forces Agreement (1999) and Enhanced Defence Cooperation Agreement (2014) were designed to preserve access without triggering the constitutional requirement.

• The 2014 EDCA represented a structural reinvention of the alliance: US access without permanent basing. The Enhanced Defence Cooperation Agreement, signed 28 April 2014 by President Aquino III and visiting President Obama, created a mechanism for rotating US military presence at Philippine "Agreed Locations" — facilities the Philippines owns but which the US may use for prepositioned equipment, training, and operations. EDCA was constructed specifically to avoid the Article XVIII Section 25 constitutional requirement by maintaining Philippine formal ownership of the facilities. Critics disputed this legal interpretation; the Supreme Court of the Philippines upheld EDCA's constitutionality on 12 January 2016.

• The Duterte presidency (2016–2022) demonstrated that the alliance was structurally resilient even against a head of government actively working to weaken it. Rodrigo Duterte's repeated threats to terminate the VFA, his invective against US officials including President Obama, and his announced pivot toward China all failed to dissolve the underlying treaty architecture. The Philippine military, the defence establishment, and the Senate majority remained pro-alliance throughout the Duterte period. When Duterte formally notified the US of VFA termination in February 2020, the notification was extended six months, then extended again, then withdrawn in July 2021. The alliance's bureaucratic and institutional depth outlasted the political turbulence at the top.

• The 2022–2024 Marcos Jr. re-pivot produced the most significant structural expansion of the alliance since the 1951 MDT itself. The April 2023 announcement of four new EDCA Agreed Locations — bringing the total to nine, with sites in northern Luzon directly relevant to a Taiwan Strait contingency and in Palawan directly relevant to South China Sea operations — reflected a Philippine strategic calculation that Chinese maritime pressure required a credible US deterrent presence. The simultaneous US statements that the MDT "ironclad" commitment applied to Philippine coast guard vessels in the South China Sea addressed the central gap exposed by the 2012 Scarborough Shoal precedent. Whether the expanded alliance deters Chinese coercion or provokes Chinese escalation remains the central strategic question.

• The relationship's legitimacy in the Philippines depends on whether it is perceived as serving Philippine security interests or primarily as US strategic infrastructure for regional power competition. The Taiwan Strait framing of northern Luzon EDCA sites — acknowledged by US military officials before Congress — reinforces Filipino anxieties that the Philippines is being positioned as a forward platform for a war it will not start, cannot control, and would suffer catastrophic consequences from. The Marcos Jr. administration has sought to frame EDCA expansion as enhancing Philippine sovereignty and security rather than subordinating it. This framing is contested domestically, and the tension between alliance value and entanglement risk is unlikely to be resolved by rhetorical positioning alone.

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2. Colonial Origins: The Treaty of Paris and the Philippine-American War (1898–1902)

2.1 Spain's Cession and Filipino Exclusion

The strategic relationship between the United States and the Philippines began not with a negotiation between the two parties but with a commercial transaction between two external powers. The Treaty of Paris, signed 10 December 1898, concluded the Spanish-American War and transferred sovereignty over the Philippine archipelago from Spain to the United States for $20 million. Filipino negotiators were not present at the Paris talks; the nascent Philippine Republic under Emilio Aguinaldo, which had declared independence from Spain on 12 June 1898 and had been actively assisting American forces, was not recognised as a party to any disposition of Philippine sovereignty.

President William McKinley's justification for annexation, as he communicated it to a delegation of Methodist ministers in November 1898, was threefold: that there was no alternative because returning the Philippines to Spain would be "cowardly and dishonorable"; that turning them over to France or Germany — "our commercial rivals in the Orient" — would be "bad business and discreditable"; and that the Filipinos were "unfit for self-government." McKinley's invocation of a divine obligation to "educate the Filipinos, and uplift and civilize and Christianize them" — in a country where Roman Catholicism had been established for three centuries of Spanish colonisation — revealed the extent to which American annexation was constructed through racial and civilisational hierarchies rather than geopolitical calculation, even as the strategic value of Manila Bay as a Western Pacific naval base drove the underlying decision.

2.2 The Philippine-American War: Scale and Consequence

Filipino resistance to American annexation began with the outbreak of hostilities on 4 February 1899, conventionally dated to shots fired near the San Juan Bridge in Manila. The war that followed was asymmetric in technology and material, but the Filipino forces under Aguinaldo and later under a dispersed guerrilla command demonstrated prolonged capacity for resistance. The American military campaign employed tactics — concentration camps, "water cure" torture, mass destruction of villages — that generated considerable controversy in the United States, where an Anti-Imperialist League including Mark Twain, Andrew Carnegie, and former President Grover Cleveland opposed annexation on both moral and constitutional grounds.

The human cost of the war fell overwhelmingly on Filipinos. American military deaths numbered approximately 4,200. Filipino combatant deaths have been estimated at approximately 20,000. The civilian death toll, which includes deaths from direct violence, famine, and the cholera epidemic worsened by wartime conditions, has been estimated at figures ranging from 200,000 to over one million; the lower figure of approximately 200,000 is most commonly cited in the scholarly literature but remains TBD-VERIFY pending authoritative demographic reconstruction. The Philippines Commission formally declared the war ended on 4 July 1902, though organised resistance in some regions — including the Moro provinces of Mindanao — continued well beyond that date.

The Philippine Organic Act of 1902 established the framework for civilian colonial administration, creating a bicameral Philippine Commission (upper house, all American-appointed) and a Philippine Assembly (lower house, elected). The trajectory it established — progressive Filipinisation of governmental institutions against a backdrop of American retention of ultimate sovereignty — would culminate, through the 1916 Jones Act (which created a fully elected bicameral legislature), the 1935 Tydings-McDuffie Act (which established the Philippine Commonwealth and set a ten-year path to independence), and the 1935 inauguration of Manuel Quezon as the first Commonwealth President.

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3. Wartime Alliance and the Independence Settlement (1935–1946)

3.1 MacArthur, Bataan, and the Pacific War

The Commonwealth period produced a significant military relationship in the form of General Douglas MacArthur's appointment as Field Marshal of the Philippine Army in August 1936 — a role he took on retirement from the US Army, though he remained available for recall. When Japan attacked the Philippines on 8 December 1941 (simultaneous with the Pearl Harbor attack across the International Date Line), MacArthur was recalled to active US service as commander of US Army Forces in the Far East.

The subsequent military campaign became one of the most consequential and symbolically charged episodes in the bilateral relationship. The fall of Bataan on 9 April 1942 and Corregidor on 6 May 1942 produced the Bataan Death March — the forced transfer of approximately 75,000 Filipino and American prisoners of war under conditions of extreme brutality, during which approximately 5,000 to 18,000 Filipinos and 500 to 650 Americans died [TBD-VERIFY: Filipino death estimates span 5,000-18,000 across the historiography; harmonised with PH-F-05]. MacArthur's evacuation to Australia by PT boat on 11 March 1942, under presidential orders, and his declaration "I shall return" became the rhetorical anchor for the American commitment to Philippine liberation. His return, landing at Leyte Gulf on 20 October 1944, fulfilled that commitment and entered the mythology of the alliance.

The war years forged bonds of shared sacrifice that provided genuine emotional and political content to the post-independence alliance — content that subsequent treaty negotiations about basing rights and trade privileges could not have manufactured on their own. The joint defence under fire, the Filipino guerrilla resistance that maintained communication with MacArthur's command throughout the occupation, and the liberation campaign created a narrative of alliance as partnership that persisted in Philippine political culture even as the structural terms of the post-independence settlement were recognised as asymmetric.

3.2 The Independence Settlement: Sovereignty and Dependency (1946)

The Philippines achieved formal independence on 4 July 1946 — Independence Day date chosen by Washington, not Manila, which would later shift its national celebration to 12 June (the 1898 Aguinaldo declaration). The independence was accompanied by instruments that preserved the economic and strategic integration developed under colonialism.

The Bell Trade Act of 1946, required by the US Congress as a condition of reconstruction assistance under the Philippine Rehabilitation Act, gave American citizens and corporations equal rights with Filipinos in exploiting Philippine natural resources and operating public utilities — a provision that required an amendment to the Philippine Constitution, since the original 1935 Constitution had restricted such rights to Filipino nationals. Philippine acceptance of these parity rights was extracted in the context of $620 million in war damage rehabilitation payments, a figure that made refusal practically difficult. The parity provisions remained in force until 1974.

The 1947 Military Bases Agreement, signed 14 March 1947, formalised US retention of 23 military installations on a 99-year lease. The two strategically decisive facilities were Clark Air Base in Angeles, Pampanga — the largest US air base outside the continental United States — and Subic Bay Naval Station in Olongapo, Zambales — the largest US naval facility in the Pacific. The lease was subsequently renegotiated in 1966 to run until 1991, with annual rental payments introduced. The 1947 agreement also contained provisions on criminal jurisdiction over US personnel that became a recurring source of nationalist grievance: US servicemen accused of crimes against Filipino citizens were subject to different jurisdictional rules than Philippine law would otherwise provide.

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4. Cold War Architecture: The MDT, Magsaysay, and Marcos (1947–1986)

4.1 The Mutual Defence Treaty (1951)

The legal bedrock of the alliance is the Mutual Defence Treaty signed 30 August 1951, ratified by the US Senate and the Philippine Senate, and entering into force 27 August 1952. The MDT's core operative provision — Article IV — states that each party "recognizes that an armed attack in the Pacific Area on either of the Parties would be dangerous to its own peace and safety and declares that it would act to meet the common dangers in accordance with its constitutional processes." The language is notably softer than the NATO treaty's Article 5 ("shall be considered an attack against them all"), and the phrase "would act to meet the common dangers in accordance with its constitutional processes" was understood from the start to preserve US congressional authority rather than create an automatic trigger.

The MDT applied to "an armed attack on the metropolitan territory of either of the Parties, or on the island territories under its jurisdiction in the Pacific or on its armed forces, public vessels or aircraft in the Pacific." The scope of "island territories under its jurisdiction in the Pacific" was understood at the time of signing to refer to Philippine territory as then internationally recognised. Whether it encompassed features in the South China Sea — Scarborough Shoal, the Kalayaan Island Group — which the Philippines would claim in subsequent decades was left deliberately unaddressed. This ambiguity, compounded by the 2012 Scarborough Shoal episode, generated the most sustained strategic uncertainty in the alliance's history until the 2023 Biden-Marcos clarifications.

4.2 The Magsaysay Era: Maximum Alignment (1953–1957)

Ramon Magsaysay's presidency (1953–1957) represented the closest ideological and operational alignment in the bilateral relationship. Magsaysay had served as Secretary of National Defence under President Elpidio Quirino, where he worked closely with CIA officer Edward Lansdale on the suppression of the Huk Rebellion — the armed communist insurgency that had emerged from wartime anti-Japanese resistance and post-war disillusionment with the independence settlement. The Lansdale-Magsaysay collaboration produced a counterinsurgency model combining military operations, intelligence penetration, civic action, and psychological warfare that Lansdale subsequently attempted to replicate in Vietnam.

Magsaysay's election as president in November 1953, which the CIA supported through assistance to his campaign (TBD-VERIFY), placed in Malacañang a leader who was genuinely aligned with American Cold War objectives, genuinely popular domestically, and genuinely committed to democratic governance within the context of the US alliance. His death in a plane crash on Mount Manunggal, Cebu, on 17 March 1957 removed from the bilateral relationship its most successful iteration of a Philippine leader who combined domestic legitimacy with close alliance management — a combination that his successors, in different ways, all struggled to achieve simultaneously.

4.3 US Bases, Nationalism, and Renegotiation (1959–1972)

The period from the late 1950s through the early 1970s was characterised by recurring nationalist pressure on the bases agreement. The bases were the most visible symbol of Philippine dependence on the United States, and incidents involving American servicemen — crimes against Filipino civilians with jurisdictional complications, accidents outside the bases that killed Filipino bystanders — provided recurring mobilisation focal points for nationalist organisations and opposition politicians.

The 1966 renegotiation under President Ferdinand Marcos (in his first term, before martial law) shortened the lease from 99 years to 25 years (expiring 1991) and introduced annual rental payments — initially $14 million, later negotiated upward — that gave the arrangement at least the form of a commercial transaction rather than a colonial grant. Marcos also gained American acquiescence to a Philippine claim of sovereignty over the bases, even as US operational control remained. These adjustments addressed the most visible formal asymmetries while preserving the strategic substance of American access.

4.4 US Support for Marcos under Martial Law (1972–1986)

Ferdinand Marcos declared martial law on 21 September 1972, citing the communist New People's Army insurgency and the Muslim separatist Moro National Liberation Front as justifications. (→ PH-B-03.) The United States, which maintained Clark and Subic Bay as irreplaceable strategic assets in the context of the Vietnam War and its aftermath, made a consistent Cold War calculation that the bases required a stable Philippine government, and that Marcos — whatever his domestic governance — provided that stability.

The Nixon administration, which received Marcos and Imelda at the White House in September 1966 and maintained warm relations through the martial law declaration, continued substantial military and economic assistance. The Ford administration similarly provided support. The Carter administration, with its human rights emphasis, created some friction — human rights conditions were attached to military aid, generating Marcos's public resentment — but did not fundamentally alter the strategic relationship. The Reagan administration, which took office in January 1981, was explicitly warmer toward Marcos; Vice President George Bush attended Marcos's inauguration in July 1981 and toasted his "adherence to democratic principles and to the democratic processes."

The record of US support for Marcos under martial law is extensively documented in Bonner's Waltzing with a Dictator (1987), which drew on State Department cables and congressional testimony to demonstrate the extent to which American officials were aware of the Marcos government's human rights abuses — summary executions, torture of detainees, arbitrary detention of political opponents — and chose strategic continuity over accountability. This record became, after EDSA, the principal exhibit in the nationalist argument that the alliance served American interests at Filipino expense.

4.5 EDSA and the US Withdrawal of Support (February 1986)

The EDSA People Power Revolution of 22–25 February 1986 succeeded in removing Marcos partly because of a decisive shift in the US position in the revolution's final hours. (→ PH-B-05.) When Marcos's long-standing political and military consolidation began to fracture — with Defence Minister Juan Ponce Enrile and AFP Vice-Chief of Staff General Fidel Ramos announcing their defection on 22 February, and Cardinal Jaime Sin calling on Filipinos to protect them — the strategic question became whether Washington would support a Marcos counterattack against the EDSA crowd.

Reagan administration officials, including Ambassador Stephen Bosworth and Assistant Secretary Paul Wolfowitz, communicated through private channels that the United States would not support the use of military force against civilian demonstrators. On 25 February, after Marcos and Aquino had both taken oath-of-office ceremonies (Marcos in Malacañang, Aquino at Club Filipino), the Reagan administration formally recognised Corazon Aquino as President of the Philippines and urged Marcos to accept a "peaceful transition." Marcos and Imelda departed Malacañang that evening for Clark Air Base, were transported by US military aircraft to Hawaii, and went into exile.

The US role in EDSA — signalling that force would not be supported, providing transportation for Marcos's departure — has been interpreted variously as a principled US commitment to democratic transition and as a pragmatic calculation that Marcos had become a liability who could be replaced by a more legitimising partner without sacrificing the strategic assets. Both interpretations contain truth, and neither resolves the central tension: that the same alliance that had sustained Marcos through fourteen years of dictatorship facilitated his removal when he became untenable.

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5. The Post-EDSA Constitution and the End of the Bases (1986–1992)

5.1 Article XVIII Section 25: The Constitutional Framework

The 1987 Constitution, ratified in February 1987 as the foundational document of the post-Marcos democratic restoration, addressed the bases question directly in its transitory provisions. Article XVIII Section 25 provided: "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 and, when the Congress so requires, ratified by a majority of the votes cast by the people in a national referendum held for that purpose, and recognized as a treaty by the other contracting State."

This provision reflected a deliberate constitutional choice to require Senate ratification for any continuation of the bases — precisely to prevent an executive from simply renewing the arrangement by executive agreement as a fait accompli. The threshold was 16 votes (two-thirds of the 24-member Senate). The provision also required that the treaty be "recognized as a treaty by the other contracting State" — meaning the US Senate would also need to treat the arrangement as a treaty, not merely as an executive agreement.

5.2 The Pinatubo Factor and the Treaty Negotiation

Negotiations for a new bases treaty began in 1990. The eruption of Mount Pinatubo on 15 June 1991 — the second largest volcanic eruption of the twentieth century — effectively pre-decided the fate of Clark Air Base, which was covered by volcanic ash and rendered operationally unusable. This geological event removed one of the two major facilities from the equation, concentrating the debate on Subic Bay Naval Station, which had escaped major Pinatubo damage.

The negotiated Treaty of Friendship, Cooperation, and Security, initialled in August 1991, provided for a ten-year US lease of Subic Bay at an annual rental of $203 million. Philippine negotiators, led by Secretary of Foreign Affairs Raul Manglapus, obtained significant improvements over the 1947 arrangement in terms of Philippine sovereignty over the base, criminal jurisdiction provisions, and rental terms. US negotiators, led by Richard Armitage, sought to minimise constraints on operational flexibility.

5.3 The 12–11 Senate Vote (16 September 1991)

The Philippine Senate voted on the treaty on 16 September 1991. The outcome — 12 votes against, 11 in favour — rejected the treaty by a single vote and precluded the two-thirds majority required under Article XVIII Section 25. The result was reached in the context of a sustained public debate in which nationalist sentiment — grounded in both the colonial legacy and the martial law complicity record — mobilised significantly against the treaty, while the Aquino administration, the business community, and the US government argued for retention on strategic and economic grounds.

The senators who voted against included former Senator Aquilino Pimentel Jr., Senator Wigberto Tañada, and Senator Rene Saguisag — all associated with the democratic opposition tradition and nationalist politics. The vote was a constitutional exercise of Philippine sovereign will, and it resolved — at least for the immediate period — a question that had been contested since 1947. Clark Air Base was formally closed in November 1991; Subic Bay Naval Base was returned to the Philippine government on 24 November 1992, becoming the Subic Bay Freeport Zone.

The closure of the bases transformed the alliance's institutional basis. Without permanent basing, the MDT became a commitment without the physical infrastructure that had given it operational content. The challenge of the post-bases period was to reconstruct a working alliance relationship within the constitutional constraints established by the 1987 document.

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6. The Post-Bases Architecture: VFA, JSOTF-P, and Scarborough (1992–2014)

6.1 The Visiting Forces Agreement (1998–1999)

The Visiting Forces Agreement, signed 10 February 1998 and ratified by the Philippine Senate 27 May 1999 on a vote of 18–5, provided the legal framework for US military personnel to visit Philippine territory and to participate in joint exercises. The VFA defined the jurisdictional arrangements for US personnel — a persistent source of nationalist concern given the bases-era precedents — in terms that preserved Philippine primacy of jurisdiction while providing protections for US personnel that critics argued were excessive.

The VFA's ratification was contested. Opponents argued that it replicated the jurisdictional asymmetries of the bases agreement under new legal packaging, that the "visit" framework was a fiction obscuring a de facto semi-permanent presence, and that Article XVIII Section 25 required Senate ratification (which it received) but also required the US to recognise the arrangement as a treaty (which the US side treated as an executive agreement, not a Senate-ratified treaty). This US-Philippines asymmetry in how the VFA was classified domestically — treaty in the Philippines, executive agreement in the US — was a structural legal ambiguity that Duterte would later exploit in his termination notification.

6.2 Joint Special Operations Task Force–Philippines (2002–present)

Following the 11 September 2001 attacks and the Bush administration's global "War on Terror" framework, the Philippines became a significant partner in US counterterrorism operations. The Abu Sayyaf Group, a kidnap-for-ransom and jihadist militant organisation operating in the Sulu Archipelago and western Mindanao, had declared affiliation with al-Qaeda. Joint Special Operations Task Force–Philippines (JSOTF-P) was deployed to the Southern Philippines in early 2002 under the Visiting Forces Agreement framework, providing training, intelligence, and logistical support to Philippine Armed Forces operations against Abu Sayyaf.

JSOTF-P's mandate was constrained by Philippine constitutional provisions against foreign troops conducting combat operations on Philippine soil — US personnel were designated as "advisers" rather than combatants. The operational distinction between advisory and combat roles was, in practice, contested; documented instances of US personnel participating in operations beyond the strict advisory function generated periodic legal and political controversy. JSOTF-P's presence in Mindanao lasted through the 2000s and into the 2010s, with force levels fluctuating between several hundred and approximately 600 personnel (TBD-VERIFY), representing the largest sustained US military presence in the Philippines in the post-bases period.

6.3 The South China Sea and Scarborough Shoal (2012)

The 2012 Scarborough Shoal (Huangyan Island) standoff exposed the central gap in the MDT's practical deterrent value. In April 2012, a Philippine Navy BRP Gregorio del Pilar caught Chinese fishing vessels inside the shoal's lagoon. Chinese maritime law enforcement vessels arrived and a standoff between Philippine and Chinese government vessels lasted over two months. In June 2012, US Assistant Secretary of State Kurt Campbell brokered a "mutual withdrawal" agreement under which both the Philippines and China would withdraw their vessels from the area.

The Philippines withdrew its vessels. China did not. Chinese maritime presence at Scarborough Shoal became permanent, and Filipino fishermen were subsequently denied access to waters they had traditionally fished. The United States, despite the MDT, did not take any action to reverse China's effective seizure of the shoal. The State Department's position — that the US took no position on the underlying sovereignty dispute while committed to freedom of navigation — provided no remedy for the Philippine loss.

The Scarborough precedent became the definitive exhibit for the argument that the MDT was not a reliable security guarantee for Philippine maritime claims. It demonstrated that China could make incremental territorial gains against the Philippines without triggering US intervention under the treaty, and that US diplomatic brokerage could inadvertently assist Chinese consolidation by securing Philippine withdrawal without ensuring reciprocal Chinese withdrawal. Philippine strategic planners absorbed this lesson; it informed both the Aquino administration's decision to pursue international arbitration and the subsequent EDCA negotiations.

6.4 The Enhanced Defence Cooperation Agreement (2014)

The EDCA, signed 28 April 2014 by Philippine Defence Secretary Voltaire Gazmin and US Ambassador Philip Goldberg on the occasion of President Obama's state visit to Manila, addressed the structural gap left by the 1992 base closures through a mechanism designed to pass constitutional scrutiny. Rather than leasing bases to the United States, EDCA provided for US forces to access and use "Agreed Locations" — existing Philippine military facilities — for pre-positioning of equipment, training, and related activities. The Philippines retained title to the facilities; the US would construct and operate improvements at its own expense, with improvements reverting to the Philippines at termination.

EDCA's constitutionality was challenged before the Philippine Supreme Court on grounds that Article XVIII Section 25 required Senate ratification. The Supreme Court upheld EDCA's constitutionality on 12 January 2016 in Saguisag v. Ochoa, ruling 10-4 that EDCA was an executive agreement implementing the existing MDT and VFA rather than a new treaty requiring independent Senate concurrence. The dissent argued that EDCA's scope exceeded what the MDT and VFA could support without independent Senate ratification.

The initial five Agreed Locations were: Antonio Bautista Air Base (Palawan), Basa Air Base (Pampanga), Fort Magsaysay (Nueva Ecija), Lumbia Air Base (Cagayan de Oro), and Mactan-Benito Ebuen Air Base (Cebu). The selection reflected a strategic spread covering the South China Sea approaches (Palawan), central and northern Luzon (Basa, Fort Magsaysay), and the Visayas-Mindanao area (Lumbia, Mactan).

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7. The Duterte Disruption and Alliance Resilience (2016–2022)

7.1 Duterte's Anti-American Rhetoric and the China Pivot

Rodrigo Duterte won the May 2016 presidential election on a law-and-order platform centred on his record as mayor of Davao City and his promise of a brutal campaign against drugs and crime. (→ PH-D-02.) His foreign policy positions were less clearly articulated during the campaign, but his trajectory after inauguration on 30 June 2016 moved quickly toward confrontation with the United States and an announced pivot toward China and Russia.

Duterte's early anti-American statements were startling in their personal vehemence. At a business event in September 2016, he called President Obama a "son of a whore" (putang ina) in the context of anticipated US criticism of extrajudicial killings in the drug war, prompting the cancellation of a bilateral meeting on the sidelines of the ASEAN Summit in Laos. In October 2016, during a state visit to Beijing, Duterte announced his "separation" from the United States ("I announce my separation from the United States") and spoke of a realignment with China and Russia. Chinese President Xi Jinping hosted the visit warmly and announced $24 billion in investment and loan pledges — pledges that were largely not implemented in the subsequent years.

7.2 The VFA Termination Notification (2020–2021)

The immediate trigger for Duterte's VFA termination notification was the cancellation of the US visa of Senator Ronald "Bato" Dela Rosa, Duterte's former national police chief and a principal architect of the drug war. The visa cancellation, under a provision of US law relating to human rights violations, was interpreted by Duterte as a personal affront and as interference in Philippine domestic politics.

On 11 February 2020, the Philippine government formally notified the United States of its intent to terminate the VFA, pursuant to the agreement's 180-day termination provision. The notification would have made the VFA null on 9 August 2020. The Duterte administration extended the termination notice twice — in June 2020 (six-month extension) and in November 2020 (indefinite suspension of the termination process) — as pandemic-related US military assistance became practically significant and as Philippine military leadership consistently communicated its preference for maintaining the agreement.

The final withdrawal of the termination notification came on 30 July 2021, when the Duterte government officially restored the VFA. The episode had consumed eighteen months, generated significant uncertainty about the alliance's legal basis, and ultimately changed nothing in the formal architecture. The VFA remained in force as Duterte left office.

7.3 The Arbitration Ruling and Duterte's Shelving

The Permanent Court of Arbitration in The Hague issued its landmark ruling in Republic of the Philippines v. People's Republic of China on 12 July 2016 — two weeks after Duterte's inauguration. The tribunal ruled that China's "nine-dash line" claim had no basis in the UN Convention on the Law of the Sea, that the Spratlys features claimed by China as entitling it to an exclusive economic zone were legally rocks or low-tide elevations rather than islands, and that China had violated Philippine sovereign rights in its exclusive economic zone. China rejected the ruling as "null and void."

Duterte effectively shelved the ruling, declining to invoke it in bilateral negotiations with China and instead pursuing what he described as "friendly" relations in exchange for economic engagement. In his 2016 China visit, he explicitly stated that he would "set aside" the arbitration ruling. Philippine Foreign Secretary Perfecto Yasay confirmed to Chinese counterpart Wang Yi that the Philippines would not insist on implementation of the ruling as a precondition for engagement.

The investment and infrastructure promises exchanged for this policy — including the Kaliwa Dam project and various railway and infrastructure loans — proceeded slowly, were beset by controversy about terms and sovereignty implications, and largely did not materialise at the scale announced. By the end of the Duterte presidency, the strategic benefits of the China pivot were difficult to identify, while Chinese maritime pressure on the West Philippine Sea continued and intensified.

7.4 Alliance Durability: Military-to-Military Relations

What the Duterte period demonstrated was that the alliance's resilience lay not primarily in executive-level political relations but in military-to-military institutional relationships, congressional and Senate politics, and the strategic preferences of the Philippine defence and security establishment. AFP Chief of Staff General Eduardo Año, Defence Secretary Delfin Lorenzana, and successive national security advisers maintained working relationships with their US counterparts throughout the Duterte period, conducting joint exercises under the Balikatan framework, cooperating on counterterrorism operations in Mindanao, and communicating strategic concerns through institutional channels.

The Balikatan exercises — annual large-scale bilateral military exercises — continued throughout the Duterte period, though with modified scope in some years. JSOTF-P's advisory presence in Mindanao continued. Intelligence-sharing arrangements remained active. The institutional infrastructure of the alliance, built over decades of joint operations, officer education, and equipment standardisation, proved more durable than executive-level political rhetoric. This institutional depth is a structural feature of the alliance that distinguishes it from purely transactional relationships dependent on personal leadership alignment.

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8. The Marcos Jr. Re-Pivot and EDCA Expansion (2022–2024)

8.1 The 2022 Election and Strategic Repositioning

Ferdinand Marcos Jr. — son of the dictator removed at EDSA 1986 — won the May 2022 presidential election with 59.5% of the vote, the largest presidential mandate since the restoration of democracy. His victory represented a remarkable political rehabilitation of the Marcos family name, achieved through a sustained social-media-driven revisionism of the martial law period's historical record. His running mate, Sara Duterte (daughter of Rodrigo Duterte), won the vice-presidential race with an even larger margin.

On foreign policy, Marcos Jr.'s trajectory was sharply different from his father's Cold War relationship with the US (close alignment in exchange for support of authoritarian governance) and from Rodrigo Duterte's anti-American populism. From the early weeks of his administration, Marcos Jr. signalled a re-alignment with the United States grounded in a realistic assessment of the South China Sea security situation. China's maritime pressure on Philippine-claimed features had not abated during the Duterte period; Chinese Coast Guard vessels had been routinely harassing Filipino supply missions to BRP Sierra Madre — the deliberately grounded ship on Ayungin Shoal (Second Thomas Shoal) maintained as a territorial marker — and to Filipino fishermen at traditional fishing grounds.

8.2 EDCA Expansion: The Four New Agreed Locations (April 2023)

The centrepiece of the alliance's structural reinvention under Marcos Jr. was the announcement of four new EDCA Agreed Locations on 3 April 2023, during US Secretary of Defence Lloyd Austin's visit to Manila. The four new locations, combined with the five established under Aquino III, brought the total to nine Agreed Locations and represented a qualitative as well as quantitative expansion in the alliance's geographic scope.

The new Agreed Locations included two sites in northern Luzon — Camilo Osias Naval Station in Sta. Ana, Cagayan, and Camp Melchor dela Cruz in Gamu, Isabela — which are geographically positioned with direct relevance to the Taiwan Strait. The proximity of northern Luzon to Taiwan (approximately 200 kilometres at the Bashi Channel) means that these locations provide the US military with potential staging and access points for a Taiwan contingency that were unavailable under the five existing EDCA sites. Two additional locations — Balabac Island in Palawan and Laoag International Airport in Ilocos Norte — expand South China Sea access and northern maritime surveillance capacity respectively.

US Indo-Pacific Command (INDOPACOM) testimony before the Senate Armed Services Committee in March 2024 acknowledged the strategic value of the northern Luzon sites in the context of Taiwan Strait contingency planning, providing documentary basis for the claim that the expansion served US regional deterrence strategy as well as Philippine South China Sea interests. This acknowledgement, while strategically logical from a US perspective, provided ammunition for Philippine critics who argued that the Philippines was being positioned as a forward base for a Taiwan war it had no role in causing.

8.3 The Biden-Marcos Summit and MDT Clarification (May 2023)

President Marcos Jr.'s state visit to Washington on 1 May 2023 produced a joint statement that addressed the central ambiguity in the MDT's scope that had been exposed by the 2012 Scarborough precedent. President Biden's explicit statement that the US commitment under the MDT is "ironclad" and extends to Philippine armed forces, coast guard vessels, and aircraft anywhere in the South China Sea directly responded to the question of whether the treaty applied only to metropolitan Philippine territory or also to Philippine government assets operating in claimed maritime spaces.

The joint statement further committed the US to a Luzon Economic Corridor — a trilateral initiative with Japan announced at the G7 Hiroshima Summit in May 2023 — targeting investment in semiconductor supply chains, clean energy, and infrastructure in northern Luzon. The economic component of the summit engagement represented an attempt to demonstrate that the alliance produced tangible economic benefits for the Philippines, not only security commitments that might be honoured or not in a crisis.

8.4 West Philippine Sea Confrontations (2023–2024)

The practical test of the expanded alliance's deterrent value came in a series of escalating confrontations between Philippine government vessels and Chinese Coast Guard ships in the West Philippine Sea. Chinese CCG vessels used water cannons against Philippine Coast Guard and Navy vessels conducting resupply missions to BRP Sierra Madre at Ayungin Shoal on multiple occasions in 2023 and 2024, damaging vessels and injuring crew. Chinese maritime militia vessels also engaged in blocking manoeuvres against Philippine fishing and resupply vessels at Recto Bank and other features.

The US State Department repeatedly affirmed that these incidents triggered the MDT commitment, issuing specific statements — including a 10 February 2023 statement by Secretary of State Antony Blinken — that attacks on Philippine armed forces, coast guard vessels, aircraft, or public vessels in the South China Sea would invoke the MDT's mutual defence obligations. The trilateral US-Japan-Australia maritime exercises in the South China Sea, conducted in April 2024, demonstrated multilateral support for Philippine maritime claims and provided a visible deterrent signal.

Whether this diplomatic and rhetorical commitment translated into a credible Chinese deterrent remained contested. China did not cease its coercive activities at Second Thomas Shoal, suggesting that the MDT clarification and the EDCA expansion had not yet produced the deterrent effect that the Marcos administration sought. The Marcos administration pursued a simultaneous strategy of public transparency about Chinese coercive incidents — releasing videos and photographs of water-cannon attacks — that internationalised the disputes and built pressure on China that purely bilateral channels would not have generated.

8.5 The Luzon Economic Corridor and the Economic Dimension

The April 2024 G7 announcement of the Luzon Economic Corridor — a US-Philippines-Japan trilateral initiative targeting investment in Subic Bay, Clark, Batangas, and Manila ports as well as semiconductor and clean energy supply chains — represented the largest US economic engagement with the Philippines since the Bell Trade Act era. The corridor explicitly framed economic and security integration as complementary: semiconductor fabrication and advanced manufacturing in Luzon served both economic development and US supply chain diversification away from China and Taiwan.

The economic dimension of the 2022–2024 re-pivot was significant for the alliance's domestic legitimacy. Philippine public support for the US alliance is consistently positive in polling — significantly higher than support for China as a partner — but sustaining that support requires demonstrable economic benefits. The EDCA expansion alone, without economic accompaniment, would have been more easily framed by critics as serving US interests at Philippine sovereign risk. The Luzon Economic Corridor provided a counter-narrative in which expanded alliance ties produced investment flows, jobs, and infrastructure.

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9. Contested Record

9.1 Does the MDT Constitute a Genuine Security Guarantee?

The central contested question in the alliance is whether the MDT's mutual defence commitment is credible against Chinese coercion. The sceptical case rests on the Scarborough precedent: in 2012, China made a permanent territorial gain against the Philippines without triggering any US action under the MDT. The 2023 Biden clarifications improved the rhetorical situation but did not resolve the underlying strategic question of whether the United States would risk major power war with China over Philippine coast guard vessels at Ayungin Shoal.

The affirmative case argues that the MDT's value lies not in any automatic trigger but in the uncertainty it creates for Chinese strategic planners: because China cannot be certain the US would not respond to a major armed attack on Philippine forces, the treaty raises the risk calculus of large-scale coercion sufficiently to deter it. On this view, the incremental coercion at Second Thomas Shoal and other features falls below the MDT threshold precisely because China does not want to test the commitment at the level of armed attack. The expanded EDCA presence makes it harder for China to conduct a sudden large-scale seizure of Philippine territory without engaging US forces or assets.

Neither argument can be resolved outside a crisis, and the Philippines has consistently faced the problem that the most relevant scenario — Chinese seizure of a maritime feature using "gray zone" tactics that fall below the armed-attack threshold — is precisely the scenario that the MDT was never designed to address.

9.2 Does EDCA Serve Philippine or Primarily US Strategic Interests?

The US military's public acknowledgement before Congress that northern Luzon EDCA sites are relevant to Taiwan Strait contingency planning provided concrete evidence for the argument that the Philippines is being incorporated into US extended deterrence infrastructure for scenarios that are not primarily about Philippine security. A Taiwan conflict would be catastrophic for the Philippines — as a major remittance destination (approximately 130,000 OFWs in Taiwan as of TBD-VERIFY), as a major trading partner, and as a country that would be in the direct combat zone if the Taiwan Strait became a theatre of war.

The Philippine government's position — that EDCA expansion strengthens Philippine deterrence in the South China Sea and that the alliance benefits from mutual reinforcement — is logically coherent but depends on the argument that what deters China from attacking Taiwan also deters China from attacking the Philippines. Critics argue the causal arrow may run the other way: that US military presence in the Philippines makes the Philippines a target in a Taiwan conflict rather than a deterred party in a South China Sea dispute.

9.3 Colonial Continuity and Structural Sovereignty

The nationalist critique of the alliance, articulated in different registers from Claro Recto in the 1950s through Renato Constantino in the 1970s through contemporary critics, argues that the treaty architecture reproduces the structural conditions of colonialism: Philippine territory provides strategic infrastructure for American power projection; the economic terms of engagement (preferential market access, investment frameworks) reproduce the asymmetries of the Bell Trade Act era in new legal forms; and the alliance's legitimating narrative — shared values, democratic solidarity, alliance as partnership — obscures the persistent power asymmetry.

The counterargument is that the alliance has evolved: the 1991 Senate vote demonstrated that the Philippines could and did exercise sovereign will to close the bases; the EDCA arrangement required Philippine constitutional compliance and Supreme Court validation; and the Philippines has used the alliance framework to extract security guarantees, economic assistance, and diplomatic support that it could not have obtained outside it. The question of whether the alliance is exploitative or mutually beneficial is, on this view, a question about whether the Philippines has sufficiently leveraged the alliance for its own ends — a question of strategic capacity, not structural determination.

The historical record suggests both dimensions are simultaneously true: the alliance has served and continues to serve distinct US strategic interests that do not always align with Philippine interests, and the Philippines has at critical moments exercised sovereign agency within the alliance (the 1991 Senate vote being the clearest example) rather than simply accepting terms set by Washington. The relationship's contested nature is a feature, not a bug, of what the Philippines has had to navigate since 1898.

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10. Conclusion

The US-Philippines strategic relationship across 126 years resists reduction to either the nationalist narrative of neo-colonial subordination or the official narrative of partnership between equals. The colonial origins in conquest and annexation, the post-independence settlement that preserved economic dependency and military access, the Cold War tolerance for authoritarian governance, and the structural asymmetries in all treaty arrangements are real and historically documented. So are the instances of Philippine sovereign agency — the 1991 Senate vote, the EDCA constitutional litigation, the 2012–2016 arbitration strategy — and the alliance's demonstrated capacity to provide genuine security goods that the Philippines could not produce independently against a militarily superior China.

The 2022–2024 Marcos Jr. re-pivot, with its nine EDCA sites and Biden's explicit MDT extension to South China Sea operations, represents the most significant structural evolution of the alliance since the 1951 MDT. It has been driven by a convergence of Philippine strategic anxiety about Chinese maritime coercion and US strategic interest in forward positioning for Indo-Pacific deterrence. Whether this convergence reflects genuinely aligned interests or a tactical coincidence of different strategic priorities will be determined by how the United States responds the next time China challenges Philippine maritime claims in a way that tests the MDT commitment.

The defining structural challenge of the alliance in the coming decade is the Taiwan Strait overlap: the same EDCA sites that the Philippines needs for South China Sea deterrence are the sites that US Indo-Pacific Command identifies as relevant to Taiwan contingency planning. The Philippines has not committed to supporting US action in a Taiwan conflict, and the 1987 Constitution imposes constraints on how Philippine territory can be used by foreign military forces. Managing this overlap — extracting South China Sea deterrence value from the EDCA architecture while preserving Philippine sovereignty over decisions about Taiwan — is the central strategic management problem the Marcos administration and its successors must navigate.

The relationship's long arc from 1898 to 2024 suggests that Philippine governments have generally found ways to use the alliance's value while managing its costs, and that the alliance has survived disruptions — martial law, the 1991 bases closure, Duterte — that appeared at the time to be potentially fatal. Its resilience lies in the institutional depth accumulated over a century of military partnership, in the genuine convergence of democratic values and Pacific security interests, and in the structural reality that the Philippines, as a middle power in a contested maritime region adjacent to both China and a major US ally (Japan), has limited alternatives to managing the superpower relationship carefully rather than attempting to exit it.

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