Following their summit meeting on May 28, Philippine President Ferdinand Marcos Jr., who was visiting Japan as a state guest, and Japanese Prime Minister Takaichi Sanae issued a joint statement in which they agreed to upgrade bilateral ties to the Comprehensive Strategic Partnership level. The upgrade marks the 70th anniversary of normalized diplomatic relations and reflects the two countries’ expanding cooperation in recent years, notably in the maritime and security realms, exemplified by Japan’s first export of completed defense equipment to the Philippines in 2023 and the Philippines becoming the first recipient of Japan’s Official Security Assistance, announced in January.
Under the Comprehensive Strategic Partnership, the two leaders agreed to initiate negotiations on the General Security of Military Information Agreement (GSOMIA) as a step toward future intelligence sharing, and to examine the possibility of transferring a naval vessel from Japan to the Philippines. They also agreed to strengthen energy security cooperation through Japanese support for the Philippines in developing a national oil reserve system.
The two countries also reconfirmed their partnership for infrastructure development and trade and investment promotion through existing economic agreements, including the Japan-Philippines Economic Partnership Agreement (JPEPA), ASEAN-Japan Comprehensive Economic Partnership (AJCEP), and the Regional Comprehensive Economic Partnership (RCEP). The Philippines reiterated its interest in joining the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), and Japan expressed its support. Together, these elements reflect the two fundamental components of international relations: power and economic interest.
Some may question the sustainability of close ties, given the contentious political environment in the Philippine Senate and its reflection of great-power rivalry in Philippine domestic politics; that is, Marcos’s alignment with the United States, with Vice President Sara Duterte’s persistent distance from Marcos.
As I have argued previously, Japan-Philippines bilateral ties are institutionalized beyond politics and have remained on a steady course. Tellingly, the ratification of the Reciprocal Access Agreement (RAA) was unanimous in the Philippine Senate, despite the chamber being locked in political standoff. Even senators such as Imee Marcos, Bong Go, Bato de la Rosa, Robin Padilla, Alan Peter Cayetano, and Rodante Marcoleta, who did not join the Senate’s resolution condemning China’s remarks about a Filipino official, and who are close to the Dutertes, voted in favor of the RAA.
Given the solidity of bilateral ties anchored in shared strategic goals, the challenges ahead are likely to be regional or global rather than bilateral. Without that broader context, even landmark firsts risk fading into historical footnotes.
The joint statement also reaffirmed the guiding principle the two countries have long upheld, committing to promote “… rules-based regional architecture upholding the international laws,” and announced the start of maritime delimitation negotiations. This introduces the third fundamental component of international relations: norms.
Both Chinese and Taiwanese authorities responded immediately, in markedly contrasting tones. China claimed that talks to delimit a boundary between Japan and the Philippines were “illegal, null and void”; Taiwan’s foreign ministry said it “commends” the initiative and even suggested possible future collaboration to promote regional stability and environmental protection. The great-power rivalry makes it tempting to draw a sharp line between China and U.S. allies in the Indo-Pacific.
The quest for a rules-based order is, however, a universal one. The drafting of the United Nations Convention on the Law of the Sea (UNCLOS) is instructive: UNCLOS was not an American-led initiative imposed on the Global South but rather an expression of the newly independent states, now often counted among the Global South. Arturo Tolentino, who led the Philippine delegation to UNCLOS, recorded in his autobiography, Voice of Decent (Phoenix Pub. House, 1990), that Manila held its position in support of the 12-nautical-mile territorial sea under UNCLOS despite American opposition. Notably, the Philippines maintained that position even as a close U.S. ally during the Cold War.
The Philippines, as this year’s ASEAN chair, would do well not to let slip the opportunity to promote a rules-based maritime order underpinned by UNCLOS. Given the divergent views on the South China Sea, Manila cannot advance its interests alone. It bears recalling, though, that the Philippines won its arbitration award not to protect a sovereign claim over specific islands but to clarify what constitutes a valid claim under UNCLOS.
The Permanent Court of Arbitration’s award in favor of the Philippines has become part of international law, recognized and endorsed by many countries. Malaysia, often labeled a hedger in the context of great-power rivalry, followed the logic of the arbitration when it rejected China’s claim on its historical rights at the United Nations.
ASEAN has supported the rule of law as a mechanism for resolving disputes since its founding in 1967, and reaffirmed that position when member states adopted the ASEAN Outlook on the Indo-Pacific in 2019. As ASEAN chair, the Philippines could put that commitment on display, citing the arbitration award and member states’ maritime delimitation efforts as tangible evidence.
Japan is not a claimant state but, along with other like-minded countries, a stakeholder in the rules-based order in the South China Sea. If Japan and the Philippines double down on talks to delimit a maritime boundary between the two countries in addition to pursuing their power and economic interests, their Comprehensive Strategic Partnership could serve as a beacon in troubled waters.
