Should the 1950 Mutual Defense Treaty be reworded or modified?

On Nov. 22, 2022, while appearing in the TV news program One News: The Chiefs, National Security Adviser Clarita Carlos revealed that top Philippine security and foreign relations cluster officials were scheduled to meet to review the 1951 Philippine-U.S. Mutual Defense Treaty (MDT).

According to her, President Ferdinand Marcos Jr. ordered a review of the MDT considering several U.S. requests and proposals, particularly about the 2014 Enhanced Defense Cooperation Agreement (EDCA).

She added that the government had already formed a study group--composed of officials from the National Security Council (NSC), the Department of National Defense (DND), and the Department of Foreign Affairs (DFA)—that would study and review the MDT. She said that the study group would discuss how the 71-year-old mutual defense treaty could be reworded or modified to make it responsive to the changing times. 

This is not the first time a review of the 1951 MDT was raised. In December 2018, then DND Secretary Delfin Lorenzana announced the review of the 1951 Philippine-U.S. MDT and its relevance in the 21st century by his department. He stated that the time had arrived for the MDT “to be revisited, given that its provisions were formulated in the early 1950s.” He added that the defense department was assessing if the MDT “should be maintained, strengthened, or scrapped.”  

The changing nature of the MDT

The 1951 MDT, like other mutual defense treaties signed by the U.S. with its Asian allies, established a consultative security relationship expressed in broad terms.

It did not contain definite defense provisions nor serve as a deterrence against any armed attacks. It calls for mutual consultation rather than an automatic retaliatory response to any act of armed aggression. 

The major issue that bedevils the alliance is the clarification of U.S. security commitment to the Philippines as provided for in the 1951 MDT and as it relates to China’s maritime expansion in the South China Sea. In June 2011, Manila sought an unequivocal U.S. commitment to Philippine defense in the face of Chinese expansion in the South China Sea.

Philippine officials argued that an armed attack on Philippine forces anywhere in the Pacific, including the South China Sea, should trigger an automatic U.S. armed response.

The 1951 MDT, unfortunately, does not specify a retaliatory armed response to external armed aggression since it only requires each signatory to consult each other and determine what armed action, if any, both would take. U.S. policy remains vague and ambiguous regarding the nature of its treaty commitment. It stops short of any reference to an automatic response if an armed conflict erupts in the South China Sea.  
 
Since 2015, however, an increasing number of U.S. policymakers have supported the view that the Philippines is a strategic bellwether of China’s maritime expansion in the Western Pacific and, at the same time, the natural barrier to check China’s expansionism.

The U.S.’s ability to guarantee the Philippines’ external defense depends on whether American forces are physically prepositioned to provide an immediate response. The U.S. can defend its ally only if it has access to facilities near the South China Sea from where it can quickly react during an armed confrontation.  

Testing the MDT

Washington adopts a neutral position on the maritime sovereignty issue and leaves the ambiguity of the MDT provisions in mid-air. However, the U.S. attitude toward China became more critical in the waning years of the Trump administration, which engaged the latter in a strategic rivalry.

President Joseph Biden has decided to continue his predecessor’s policy of competing strategically with China. In late January 2021, newly appointed Secretary of State Antony Blinken underscored the MDT’s implications for the security of the two countries, specifically in the act of armed aggression against the Philippine armed forces, public vessels, or aircraft in the Pacific, which includes the South China Sea. 

On March 20, 2021, Secretary Lorenzana reported the presence of around 220 blue-hulled Chinese fishing vessels anchored in a line formation at Julian Felipe Reef (international name Whitsun Reef). The Philippine Coast Guard (PCG) alleged that the Chinese fishing boats were manned by Chinese maritime militia as early as March 7.  

On April 9, Secretary Blinken conveyed to former Foreign Affairs Secretary Teodoro Locsin Jr. Washington’s concern over the massing of Chinese maritime militia vessels in the South China Sea and reiterated the treaty’s applicability in the disputed area. The Biden administration deployed the carrier strike group, the U.S.S. Theodore Roosevelt, and the amphibious ready battlegroup, the U.S.S. Makin Island in the South China Sea in early April 2021. 

The joint vision for the alliance

The Whitsun Shoal incident presented to the Biden administration’s security officials working with their Philippine counterparts—and in conjunction with an ongoing Philippine-U.S. military exercise— the need to resist the Chinese coercive attempt to occupy a land feature inside the country’s exclusive economic zone (EEZ). This also proved the MDT’s applicability in a crisis in the South China Sea.  

Washington’s vigorous show of support to Manila during the stand-off led to a dramatic improvement in Philippine-U.S. security relations at the end of the Duterte administration.

On Nov. 16, 2022, the two countries formulated a new bilateral defense guideline that came in the form of “Joint Vision for a 21st Century United States-Philippines Partnership.” This document states the two sides’ intention to ensure the MDT’s relevance in addressing current and emerging threats and their common efforts to support a mutual understanding of the two allies’ roles, missions, and capabilities within the alliance.

These developments indicate both countries’ consensus on the need to transform the MDT from a mere consultative mechanism to an anchor that will provide stability to their alliance as they address common security challenges they will face into the 21st century.

More significantly, the joint vision for the US-Philippine Partnership showed that instead of [unilaterally] rewording or modifying the MDT to make it responsive to the changing times, the treaty should be allowed to undergo the processes of what President Marcos described as “negotiation and evolution.” 

Renato Cruz De Castro is trustee and program convenor of think tank Stratbase Institute.