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The Philippines-US Alliance at 70
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The Philippines-US Alliance at 70

The 1951 Mutual Defense Treaty became the most important element in the Philippine-U.S. alliance. How can it remain relevant in a changing Indo-Pacific?

By Renato Cruz De Castro

In December 2018, Philippine Defense Secretary Delfin Lorenzana declared during a press briefing that the Department of National Defense (DND) was reviewing the 1951 U.S.-Philippines Mutual Defense Treaty (MDT) and its relevance in the 21st century. He said that the time had arrived for the MDT “to be revisited, given that its provisions were formulated in the early 1950s.” Lorenzana explained: “We believe it is time to sit down with our U.S. counterparts and revisit the terms of our alliance. We are partners. We have deep historical ties. We must clearly define our roles and responsibilities when the need arises to be joined in arms.”

The call for a review of the MDT stemmed from Lorenzana’s and the defense establishment’s deep-seated apprehension that the Philippines might be dragged into an armed confrontation between the United States and China. This worry centered on the two powers’ military activities in the South China Sea, namely Chinese construction and fortification of several artificial islands and the U.S. Navy’s repeated freedom of navigation operations and overflights in the disputed waters. There were also anxieties within the DND and the Armed Forces of the Philippines (AFP) about abandonment by their ally, despite promises from U.S. officials that the MDT is an “ironclad” commitment that the United States will honor, even in the contested islands in the South China Sea.

The defense department’s move to subject the MDT to a review was driven by uncertainties over what the U.S. can bring to the table and what it expects from the AFP in case of an armed clash between the U.S. and China in the South China Sea. Lorenzana added that the defense department was assessing if the MDT “should be maintained, strengthened, or scrapped.”

The Philippines and the U.S. signed the MDT on August 30, 1951 in Washington D.C. It linked the Philippine-U.S. alliance to the southern-flank portion of the U.S. regional alliance network – also known as the San Francisco system – which includes the ANZUS pact, a formal defense treaty, entered into in 1951 with Australia and New Zealand. When it was signed, the MDT was never meant to the Philippines’ only bulwark against possible foreign threats that the country might face in the future. The MDT was only one of three security treaties the two allies negotiated and signed as legal instruments for balancing a clearly designated communist-related threat during the Cold War. More significantly, the MDT contains several ambiguous details on how the Philippines and the U.S. will respond to an act of armed aggression committed against either of the two parties.

How did the 1951 MDT became the most important element in the Philippine-U.S. alliance? How have the two allies used the MDT to advance their security interests? And what is the future of MDT, 70 years after it was signed?

Historical Overview of the 1951 MDT

In September 1951, on the side of the ongoing San Francisco Peace Conference, the Philippines and the United States signed what would eventually be the world’s oldest mutual defense treaty, the 1951 Philippine-U.S. Mutual Defense Treaty. Interestingly, when Manila and Washington signed the treaty, it was considered a mere supplementary agreement to a more important accord; it was not meant to be the primary deterrence against external threats the two allies might face in the Western Pacific.

Even before the MDT was signed in 1951, the Philippines had granted the U.S. basing rights through the 1947 Philippine-U.S. Military Bases Agreement (1947 MBA). That executive agreement was signed in March 1947 and provided the United States military the right to retain the use of 16 bases and access to facilities rent-free for 99 years. The bases agreement was supplemented by a military assistance pact that entered force in the same year, and then by the mutual defense treaty signed four years later. This array of agreements effectively made the Philippine-U.S. alliance part of the Pacific alliance network (otherwise known as the hub-and-spoke system of bilateral alliances) that was established by Washington during the early phase of the Cold War in the Pacific.

The MDT 1951 was a supplementary agreement to the 1947 MBA. Like other mutual defense treaties signed by the U.S. with its other Asian allies, it merely established a consultative security relationship, which was expressed in broad terms as the U.S. resisted the inclusion of any additional provisions under the agreement. It was not seen at the time as a significant deterrence against any possible attack against the Philippines since it simply provided for mutual consultation rather than automatic assistance in case of an armed attack. Article IV of the MDT states that: “Each party recognizes 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 process.” Consequently, most U.S. interpretations have fallen short of an actual guarantee or have not specified what type of assistance might be offered to the Philippines.

From 1947 to 1991, the Military Bases Agreement was deemed the central and most important agreement in Philippine-U.S. security relations. This was because the U.S. military bases in the Philippines loomed large not only in the security of the host country but for the whole of Southeast Asia. U.S. forces operating from Philippine bases secured sea and air lanes in the entire Philippines archipelago, balanced the Soviet military presence in Vietnam’s Cam Ranh Bay, and provided for the regional defense of Southeast Asia. In September 1954, U.S. Secretary of State John Foster Dulles emphasized this point when he said that, because U.S. forces were deployed in the country, any attack on the Philippines would be “an attack on both.”

MDT Becomes the Central Treaty

Two developments in the early 1990s led to the MDT’s transformation from a mere supplementary agreement to the 1947 MBA to become the legal foundation of the 21st century Philippines-U.S. alliance. First was the withdrawal of U.S. forces from Philippine bases in November 1992; and second, China’s maritime expansion in the South China Sea, which threatened a number of land features occupied by AFP units since the early 1970s.

From the 1950s to the late 1970s, the MBA was amended via the exchange of executive correspondence. The most significant was the 1958 Bohlen-Serrano Exchange of Notes that reaffirmed Philippine sovereignty over the bases and reduced the MBA’s duration from 99 to 25 years. The MBA was set to expire in 1991, and if U.S. access to the Philippines bases was to be retained, the Philippines and the U.S. needed to craft a new basing agreement. From 1990 to 1991, Washington and Manila negotiated and signed a new accord to replace the 1947 MBA – the 1991 Treaty of Friendship, Cooperation, and Security. Unfortunately, Philippine senators, predominately  against U.S. bases, rejected the agreement. The Philippine Senate’s non-concurrence to the treaty led to the withdrawal of U.S. forces from the Philippines in November 1992. This pushed both countries to reassess the utility of their alliance in the face of the uncertainties of the post-Cold War world.

Manila and Washington decided to keep the MDT in force without any amendment, however. The two allies also decided to convene the Mutual Defense Board (MDB) every three months to provide an effective mechanism for consultation on mutual security concerns. As provided by the 1958 Bohlen-Serrano Exchange of Notes, the Council of Foreign Ministers of the Philippines and the U.S. tasked the MDB with the formulation of measures or arrangements to more effectively carry out the MDT’s specified purposes and objectives. In November 1992, the MDB agreed that joint military exercises such as the annual Balikatan exercises would continue. Both sides also agreed to routine U.S. ship visits, aircraft transits, and continued assistance by U.S. forces to Filipinos in times of natural disasters and calamities. To facilitate these military exercises and occasional ship visits, the Philippines and the U.S. signed the Visiting Forces Agreement (VFA) in 1998, and the Philippine Senate concurred to its ratification in 1999.

The 1951 MDT remained in force and the MDB was established to implement the treaty through its various meetings and consultations. However, these were seen as palliative efforts that both sides could undertake to repair the previously strong and vibrant defense relations that two allies had before 1992. These stopgap agreements and arrangements were not real measures that could restore the access of U.S. forces to the Philippines on the same scale as provided by the 1947 MBA before 1992. The U.S. and the Philippines are still allies under the 1951 MDT. However, Washington significantly downgraded its political and security relations with Manila by declaring that the U.S. could not guarantee the external defense of the Philippines since U.S. forces had been deprived of vital military facilities from which they could operate.

In late February 1995, a Philippine Navy patrol ship discovered the presence of Chinese forces on Mischief Reef. In April that year, the Philippines criticized China for occupying the reef, which is only 130 kilometers from the Philippines’ westernmost island of Palawan, and accused Beijing of creeping expansion in the South China Sea. China’s occupation of Mischief Reef was followed by a series of small-scale confrontations and demonstrations by Philippine and Chinese naval units designed to underscore their respective positions in the brewing maritime row in the South China Sea. The establishment of a Chinese base on Mischief Reef in 1995 sparked the notion that China was filling up a “power vacuum” in the region’s strategic environment after the end of the Cold War, when the U.S. pursued a policy of “disengagement” from Southeast Asia symbolized by the withdrawal of its forces from the Philippine bases in 1992.

The discovery of Chinese forces on Mischief Reef led to the realization that the Philippines faced an external threat in the form of Chinese maritime expansion in the South China Sea. From the perspective of the Philippine government, the presence of Chinese forces on a land feature deep inside the Philippines’ exclusive economic zone (EEZ) signaled a revisionist agenda behind China’s emergence as regional power in East Asia. Eventually, the Philippine government realized the importance of the U.S. strategic footprint in the country and the post-1992 bilateral alliance anchored by the 1951 MDT. Philippine defense officials and ranking military officers began constantly linking the U.S. military presence, the MDT, and the Spratly dispute as they asked for the treaty’s revision to remove ambiguities regarding a U.S. response to armed attacks on Philippine forces deployed in the South China Sea.

U.S. officials replied that any armed attack on Philippine forces in the South China Sea was covered by the references to the Pacific areas in Article V of the 1951 MDT. Washington has not publicly denied the MDT’s applicability in the South China Sea. It has, however, maintained neutrality on the sovereignty issue. The U.S. also has avoided clarifying its security commitments with respect to any possible armed clash between the Philippines and Chinese forces, and has not specified what type of military or diplomatic assistance it might extend it its ally. From Washington’s perspective, some ambiguity with regard to the 1951 MDT is useful to avoid emboldening the Philippines and provoking China in the South China Sea dispute. Felix K. Chang emphasized this point in a recent article:

From the perspective of American policymakers, the Philippines’ lack of external defense capacity could incentivize Manila to use its mutual defense treaty with the United States—its only form of real power—to assert its South China Sea claims. In short, Washington fears that Manila might take some provocative action that—whether inadvertently or not—brings the United States into a direct conflict with another country, most worryingly China.

Seeking Greater Clarification

Confronted by aggressive Chinese actions in the South China Sea at the onset of his six-year term in 2010, the late Philippine President Benigno Aquino III sought U.S. naval and air support in the Spratlys. Aquino administration defense and foreign affairs officials argued that an armed attack on Philippine metropolitan territory or forces anywhere in the Pacific, including the South China Sea, should trigger a U.S. armed response.

The U.S. position remains ambiguous on the nature and provisions of the treaty’s commitment in terms of an armed attack against the Philippines. The U.S. State Department stops short of making any reference to an automatic response in case an armed conflict erupts in the South China Sea. When pressed on the issue, U.S. diplomats fall back on the ambiguous stance that since the U.S. is a treaty ally of the Philippines, “China cannot simply assert that events in the disputed South China Sea are not any of Washington’s business.”

Then-U.S. Secretary of State Hillary Clinton reaffirmed the U.S. defense commitment to the Philippines amid rising tensions between Manila and Beijing over the disputed Spratlys. During her June 23, 2011 meeting in Washington with then-Philippine Foreign Affairs Secretary Albert De Rosario she announced that the U.S. would honor both its mutual defense treaty and strategic alliance with its Southeast Asian ally. In November 2011, abroad the USS Fitzgerald, she reiterated U.S. support to the Philippines and called for an update to the defense treaty that “will require… greater support for external defense, particularly maritime domain awareness.” Clinton, however, could not categorically tell what the U.S. would do if China attacked a Philippine ship or aircraft in the South China Sea.

After the April 2012 Scarborough stand-off between the Philippines and China, Aquino asked for a definite security guarantee when he met U.S. President Barack Obama at the White House on June 8, 2012. Obama evasively answered that the U.S. would abide by its treaty obligations under the 1951 MDT.  His vague response concealed the U.S. predicament in the South China Sea dispute – although it wants to assure the Philippines of its unequivocal support, it does not intend to start an open geostrategic rivalry with China, which is a major U.S. economic partner.

Assuaging Skepticism

Lorenzana’s December 2018 call for a review of the MDT could be seen as a delicate effort to question the Duterte administration’s appeasement policy on China. The policy is based on two assumptions: First, the U.S. would not go to war against China to safeguard the Philippines. Second, because of a lack of American commitment to defend the Philippines in the face of Chinese expansion in the South China Sea, the only option for the country is to foster economic interdependence with China. Lorenzana’s effort to seek a firmer security commitment from the U.S. is actually meant to challenge the first assumption of the administration’s appeasement policy – that the U.S. would not honor its security guarantee to the Philippines in case of an armed confrontation in the South China Sea. Lorenzana needed to convince the Duterte administration that appeasement was not the only option for the Philippines.

But his effort would only bear fruit if the U.S was willing to take the risk of re-examining the 1951 MDT. The Philippines and the U.S. must adjust or modify their security arrangements to make their 70-year-old alliance mutually beneficial, relevant, and cohesive in the 21st century.

During his March 2019 visit to Manila, then-U.S. Secretary of State Michael Pompeo declared: “As the South China Sea is part of the Pacific; any armed attack on Philippine forces, aircraft or public vessels in the South China Sea will trigger mutual defense obligations under Article 4 of our mutual defense treaty.”

Pompeo’s comment was aimed at reassuring the Philippines that Washington would support its ally relative to the Chinese island-building activities and the militarization of land features in the South China Sea. In separate talks with Philippine President Rodrigo Duterte, Pompeo said: “Our commitments under the treaty are clear. Our obligations are real. The South China Sea is certainty part of an important body of water for freedom of navigation.” He also pointed out that the Trump administration had made a true commitment to ensure that “the South China Sea remains open for the security of the countries in the region, of the world, and for commercial transit.”

Taking a Proactive Approach

Washington still maintains its neutrality over the sovereignty issue and ensures certain ambiguities in the MDT. However, recent U.S. attitudes toward China have become more critical in the last four years as the Trump administration engaged in more strident strategic competition with China. From Washington’s perspective, Beijing is an authoritarian state, driven by Communist ideology, bent on becoming the world’s dominant power by using methods of competition in violation of international law. In U.S. President Donald Trump’s last full year as president, the U.S. openly challenged China’s expansive claims in the South China Sea as it clarified that the MDT would obligate the U.S. to honor its treaty commitments to the Philippines.

When he entered office in early 2021, new U.S. President Joe Biden decided to pursue his predecessor’s policy of engaging China in a strategic competition. In late January 2021, newly appointed Secretary of State Antony Blinken called his Philippine counterpart to convey that a strong Philippine-U.S. alliance is vital to a free and open Indo-Pacific region. Blinken reiterated the MDT’s implications for the security of the two countries, specifically in case of an armed attack against the Philippine armed forces, public vessels, or aircraft, in the Pacific, including the South China Sea.

On March 20, 2021, Lorenzana officially informed the Filipino nation about the presence of around 220 blue-hulled Chinese fishing vessels moored in a line formation at Julian Felipe Reef (internationally known as Whitsun Reef). According to Lorenzana, the Philippine Coast Guard sighted and reported the presence of the Chinese fishing vessels, allegedly manned by the Chinese maritime militia, as early as March 7.  Accordingly, the behavior of the ships displayed the Chinese application of a strategy marked by claiming submerged land features through swarming disputed waters with a huge flotilla, defying the efforts of other countries’ diplomatic or law enforcement to expel it.

Analysts saw the stand-off as a Chinese gambit to exert leverage against the Biden administration on the South China Sea and to influence the outcome of the then-ongoing VFA negotiations between the Philippines and the U.S. In late March, U.S. National Security Advisor Jake Sullivan called his Filipino counterpart, Secretary Hermogenes Esperon, to emphasize U.S. support to the Philippines, and the applicability of the MDT to the area. On April 9, Blinken called Philippine Foreign Secretary Theodoro Locsin to express Washington’s concern over the massing of Chinese maritime militia vessels in the South China Sea, and more importantly, to reaffirm the applicability of the 1951 MDT in the South China Sea. U.S. Secretary of Defense Lloyd Austin called Lorenzana to express U.S. support to its ally and to inform his Philippine counterpart that the aircraft carrier USS Theodore Roosevelt and its escorts were operating in the South China Sea. Clearly, instead of being distracted by China’s actions in the South China Sea, the Biden administration was quick to express support to the Philippines as it deployed the USS Roosevelt and the USS Makin into the region in early April 2021.

Duterte, however, rejected the U.S. offer of assistance. Instead, he made a scathing rebuke against the U.S., expressing that it was doubtful whether or not the Philippines could count on its ally in case of a full-blown conflict in the West Philippine Sea, as the South China Sea is commonly called in the Philippines. Nevertheless, the incident showed top Biden security officials working with their Philippine counterparts – and in conjunction with an ongoing Philippine-U.S. military exercise – to counter Chinese coercive attempts to occupy land features inside the Philippine EEZ; while at the same time, reaffirming the importance of the 1951 MDT with the Philippines.

Conclusion

The MDT was signed in 1951 as a supplementary agreement to the 1947 MBA. It was considered at the time a mere appendage to the primary legal basis of the Philippine-U.S. alliance, which was the initial basing agreement. The withdrawal of U.S. forces from their Philippines bases in 1992, and China’s maritime expansion in the South China Sea in the late 1990s, transformed the MDT from a mere supplement to the central treaty undergirding the Philippine-U.S. alliance.

The MDT is still force, despite the withdrawal of U.S. forces from the Philippines. Nevertheless, it is still ambiguous in terms of its details on whether or not the United States would come to the assistance of the Philippines in case of an armed clash with China in the South China Sea. Washington’s reluctance to clarify the treaty’s details provides it leeway to prevent the Philippines from engaging in provocative actions against China in the South China Sea.

The late Philippine President Aquino sought to clarify the U.S. security guarantee to the Philippines as he challenged China’s expansive claims in the South China Sea during his six-year term from 2010 to 2016. Current Philippine Defense Secretary Lorenzana also sought greater clarity regarding how the U.S. would respond to any armed contingency in the South China Sea as part of an effort to question the Duterte administration’s appeasement policy on China. In the light of China-U.S. strategic competition, the Trump administration accommodated Lorenzana’s query regarding the applicability of the MDT in the South China Sea. The subsequent Biden administration has also affirmed the applicability of the MDT to a crisis in the South China Sea as it offered military assistance to the Philippines during the recent Whitsun Reef crisis.

The two allies are soon to commemorate the 70th anniversary of their formal treaty alliance. At this point in time, it is necessary for the Philippines and the U.S. to seek the Goldilocks Principle – not too hot, not too cold – in their security relationship: Washington addressing Manila’s valid concerns about the ambiguity of its security commitments while encouraging its longest treaty ally to behave responsibly in the face of China’s coercion and maritime expansion in the South China Sea.

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The Authors

Renato Cruz De Castro is a full professor in the international studies department, De La Salle University, Manila, and holds the Charles Lui Chi Keung Professorial Chair in China Studies

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