Priorities for the Emerging U.S.-Japan-Philippines Triangle

Mr. Brian Harding
Senior Expert, Southeast Asia and Pacific Islands, U.S. Institute of Peace
Publication Date: February 14, 2024

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This report is based on the findings from a research trip to Tokyo in December 2023, as well as six visits to the Philippines from 2022-2023.


In recent years Washington and Tokyo have steadily increased their engagement with Southeast Asia in line with the region’s rising geopolitical importance and Southeast Asia’s emergence as an engine of economic growth. The region welcomes deep U.S. and Japanese engagement but also considers China to be an integral and enduring part of regional affairs. While Japan is seen to be part of the neighborhood and regularly polls as Southeast Asia’s most trusted partner, the United States is considered to be distant and ultimately unreliable.[1] The result is hedging, with Southeast Asian countries making crystal clear that they will not choose between great powers and adopting strategies to insulate themselves as much as possible from geopolitical currents.

However, a major change has been underway since June 2022 in the Philippines, arguably the most strategically important country in Southeast Asia, located 118 miles from Taiwan at one end and with a front row seat to Chinese efforts to turn the South China Sea into a Chinese lake at the other. President Ferdinand Marcos, Jr. has turned Philippines foreign policy on its head following former President Rodrigo Duterte’s efforts from 2016-2022 to “separate” the Philippines from the United States and move closer to China.[2]

Marcos has taken significant steps to deepen its alliance relationship with the United States and has undertaken a policy to draw as much international attention to Chinese harassment of Philippines vessels in the South China Sea as possible. Marcos’ first year and a half have seen a flurry of high-level U.S.-Philippines diplomacy and most importantly renewed efforts to implement and expand the 2014 Enhanced Defense Cooperation Agreement which would enable rotational U.S. military presence at scale at military facilities across the Philippines. Marcos’s National Security Policy clearly supports the Armed Forces of the Philippines’ pivot from internal security to territorial defense, although a hopeful but fragile peace process in Mindanao will first need to come to a successful conclusion in 2025.[3]

But the United States and China do not stand alone as major powers that shape Philippines foreign policy – Japan sits as a key third pole for the Philippines.[4] And alongside a resurgence in U.S.-Philippines relations has been a less-noticed development – the rapid emergence of a U.S.-Philippines-Japan triangle as well as the beginnings of a U.S.-Philippines-Japan-Australia quadrilateral relationship.

With closely aligned interests, shared alliance ties with the United States, and geographical proximity (considering U.S. presence in Japan), the U.S.-Philippines-Japan triangle is a natural grouping that has been waiting for its political moment. That time has now arrived, as demonstrated in the last year with high level meetings between every top official apart from the President of the United States.

The task now is to operationalize trilateral cooperation by identifying practical areas on which trilateral action would be effective and to develop structures and networks – both government and non-government – to drive and sustain cooperation.

This paper outlines the state of trilateral relations, provides views from Tokyo and Manila based on extensive interviews, and offers recommendations for key priorities for trilateral cooperation.

Three Legs and Three Poles

All three legs of the U.S.-Philippines-Japan triangle comprise robust, mature relationships. Under the current leaders of the three countries, there are no weak links.

U.S.-Philippines Relations

The Philippines was the United States’ one major colonial possession, a fact that today both binds the two countries through history and deep interpersonal ties but also strains relations. The two countries are bound by a 1951 Mutual Defense Treaty and the United States maintained its largest overseas bases during the Cold War in the Philippines. In 1991, the Philippines Senate voted to end the U.S. military presence and security relations only began to recover after the signing of a Visiting Forces Agreement in 1999 and the deployment of U.S. Special Forces to combat Al-Qaeda-linked terrorists in Mindanao beginning in late 2001.

Meanwhile, the capacity of the Armed Forces of the Philippines (AFP) atrophied and when the Philippines began to grapple with the seriousness of its dispute with China in the South China Sea in the early 2010s, it became apparent that the Philippines’ only strategic asset for territorial defense was its treaty alliance with the United States. With the legacy of large, permanent U.S. bases hanging over deliberations, in 2014 the two sides signed the Enhanced Defense Cooperation Agreement as a vehicle for a return of U.S. military forces to the Philippines although with a far lighter footprint and on AFP bases. It also envisioned EDCA as being a bridge toward a future in which the AFP could manage territorial defense on its own.

President Rodrigo Duterte, upon taking office in 2016, sought to “separate” the Philippines from the United States, halting momentum in the alliance relationship and on EDCA. However, Duterte was swimming against the current, both in terms of public opinion and the orientation of all key players in the bureaucracy, especially the Armed Forces of the Philippines (AFP). Japan, toward which Duterte was far more favorably disposed, meanwhile played a key role in moderating some of Duterte’s worst instincts on the U.S. alliance. Ultimately, the alliance survived, but progress on EDCA was meager. Since 2022, under President Marcos the Philippines has doubled down on the alliance with the United States, expanding the parameters of military cooperation, including rotational U.S. presence, but the two sides are now making up for lost time. However, with November’s U.S. election approaching, now many in Manila are bracing for a potential slowdown due to the uncertainties of U.S. politics.

Japan-Philippines Relations

Japan-Philippines relations are positive and have been comparatively stable over time, without the wild fluctuations that have characterized U.S.-Philippines relations. However, some areas of the relationship are significantly more developed than others.

Japan-Philippines relations draw their greatest strength from the economic relationship and Japan’s contributions to economic development and domestic stability in the Philippines. Economically, Japan is seen as a reliable partner and while Japanese investment in the Philippines lags FDI in other Southeast Asian countries, it is significant in the Philippines context and is widely expected to accelerate as absorptive capacity in other Southeast Asian countries wanes. As Japan’s top Official Development Assistance recipient, the Philippines occupies pride of place within JICA and programming over decades has contributed to positive attitudes toward Japan. Most importantly, Japan has been a major contributor to Mindanao, where peace and development is a high priority for officials in Manila.[5] Meanwhile, despite close business ties and ties developed through decades of economic development partnerships, the Philippines has only recently vaulted into the top orbit of priorities for senior national security officials and experts.

The Philippines is often cited as a partner for “firsts” for Japan. For instance, since 2002, Japan has been heavily engaged on-the-ground in Mindanao in support of the peace process, marking the first major Japanese government engagement in a conflict zone since 1945. In 2013, the Maritime Self Defense Force’s HADR mission to respond to destruction from Typhoon Haiyan was the first significant overseas deployment of military personnel since 1945.

Most recently, in November 2023 the Philippines was the recipient of Japan’s first Overseas Security Assistance project through a $4 million project to provide the AFP with coastal radar systems.[6] In 2020, the Philippines also became the first destination for a defense equipment sale following 2014 reforms, with a $90 million deal for air surveillance systems.[7] Japan is currently negotiating a defense forces reciprocal access agreement that would be its third after Australia and the United Kingdom in addition to the U.S. Visiting Forces Agreement, which will facilitate Japanese Self Defense Force deployments to the Philippines for mission sets other than humanitarian assistance and disaster relief.

U.S.-Japan Relations

U.S.-Japan relations have recovered from the uncertainty of the Trump Presidency but are entering another period of uncertainty ahead of U.S. elections in November 2024. Tokyo is concerned that a second Trump administration would follow through on threats to withdraw forces from South Korea or even allow China to take Taiwan. This uncertainty, which will last until at least November, has officials in Japan considering how to advance its regional security interests absent the United States as a reliable ally and counterweight to China. In this scenario, deepening ties with Manila could become even more important.

The three poles of the triangle, however, are diverse. The United States is a superpower, with the world’s biggest economy and military, but it is seen to be distant from the Western Pacific and its ability to encourage its companies to invest in particular locations like the Philippines is scant. Japan is the world’s fourth largest economy and a major investor in Southeast Asia with a world-class military and voluminous soft power but maintains significant post-War constraints on its military and security engagement. The Philippines’ economy is fragile, and its military is underdeveloped, but its strategic location is irreplaceable.

Nascent Trilateralism

In June 2023, the three countries’ National Security Advisors met for the first time in Tokyo and outlined a vision for trilateral cooperation focused on 1) enhancing trilateral defense and security capabilities, 2) maintaining a free and open maritime order, 3) humanitarian assistance and disaster relief, and 4) maintaining a free and equitable economic order.[8]

In July 2023, the three countries’ Foreign Ministers met for the first time on the sidelines of the ASEAN Regional Forum in Jakarta and again in September 2023 at the UN General Assembly in New York. President Marcos, Prime Minister Fumio Kishida, and Vice President Kamala Harris also met in September 2023 on the sidelines of the East Asia Summit, a meeting that presumably would have included President Joe Biden had he attended the Summit.[9] In December 2023, the three countries’ National Security Advisors quickly conducted a trilateral phone call to support the Philippines position on aggressive Chinese actions within the Philippines’ exclusive economic zone, something that never would have occurred absent the rapid development of habits of trilateral cooperation. Prior to this flurry of activity in the second half of 2023, the only previous examples of trilateral coordination were coordination talks between the three militaries beginning in 2018.[10]

Words have also begun to be met with action with a first trilateral Coast Guard exercise in June 2023.[11] Once a reciprocal access agreement is signed, Japan will become a participant in major U.S.-Philippines exercises such as Balikatan, to which it has only sent observers to date.

However, beyond these ad hoc meetings, structures have not yet been developed to drive cooperation like those that have developed to guide the U.S.-Japan-Australia triangle such as the Trilateral Strategic Dialogue between the three foreign ministries and the Security and Defense Cooperation Forums involving these Ministries and their Defense counterparts.

Outside of government, three notable track two trilateral dialogues have taken place, two organized by the Center for Strategic and International Studies and one by Pacific Forum, which are beginning to knit together non-government, security-focused counterparts from the three countries. Outcomes from these events have also focused on the potential for trilateral maritime security cooperation.[12]

Key Findings

In a robust series of meetings in Tokyo in December 2023 with Japanese officials, academics, think tank experts, and media to explore perspectives on the U.S.-Japan-Philippines triangle, the author found the following:

  • Top Japanese officials are focused more on the Philippines than ever before. While Southeast Asia has for decades been a priority for Japanese business and economic development programs, Japan has recently also begun to wield its natural strategic weight in the region. This new push was first driven by Prime Minister Abe who raised Southeast Asia’s strategic profile in Japanese foreign policy in line with the region’s centrality to the Indo-Pacific regionalism and competition with China. As it has deepened ties with Southeast Asian countries, Japan has put equal weight to relationships with the major countries of Southeast Asia and has not ignored the region’s smallest members. However, the opening created by President Marcos’ bold foreign policy moves is now putting the Philippines at the top of Tokyo’s priority list for Southeast Asia with officials seeking to advance a range of clearly shared interests, especially in the maritime domain.
  • Top Japanese national security officials and experts have little experience with the Philippines. While Japan-Philippines relations are deep in some areas, national security elites in Japan have little experience with the Philippines and lack meaningful relationships with Philippines counterparts. Creating forums for U.S.-Japan alliance managers and experts to engage with counterparts from the Philippines will therefore be important for building trilateral relations over time. This dynamic is not different than among U.S. experts on Japan and the Philippines, which also exist in separate networks and in the case of U.S.-Philippines relations are a small group. Only in the Philippines are top officials and experts steeped in relations with both countries.
  • Maritime security cooperation is the most natural area for trilateral cooperation. Unsurprisingly, as three maritime countries deeply concerned with Chinese aggression in the East and South China Seas, maritime security is the most natural area for trilateral cooperation. It is also the area most likely to drive trilateral habits of cooperation given the practicality of this area of cooperation. For the foreseeable future, the Armed Forces of the Philippines will need major capacity building support, which the United States and Japan are well positioned to help deliver in a coordinated fashion. U.S.-Japan and U.S.-Philippines interoperability, shared alliance relationships, the United States and Japan’s clear position as the Philippines’ most important partners, and minimal competition between U.S. and Japanese defense industry mean coordination of assistance has the potential to be smooth. Japan’s ability to make the Philippines its top priority for its new Official Security Assistance program has the potential to offset the United States’ perennial inability to rebalance Foreign Military Assistance funding toward Asia.
  • Support for the peace process in Mindanao is a central pillar of Japan-Philippines relations. While often off the radar internationally, Mindanao is central to national security policy in the Philippines. The 2014 Comprehensive Agreement on the Bangsamoro, signed between the Government of the Philippines and the Moro Islamic Liberation Front (MILF), and the establishment in 2019 of the Bangsamoro Autonomous Region in Muslim Mindanao offer the greatest opportunity in generations for a durable peace in Mindanao, which is necessary for Manila to truly pivot to a national security policy focused on territorial defense.[13] However, the peace is fragile and will be tested by elections in 2025 that will bring a political transition period to end.[14]Manila considers Tokyo to be by far the most important international supporter of the peace process for more than twenty years, a point of pride among peacebuilding officials and practitioners in Tokyo. Key Japanese contributions have included the following: 1) when other international partners withdrew in 2008 from an International Monitoring Team amid violence, Japan increased its support, 2) before a peace agreement was reached 2014, Japan was already engaging the MILF and therefore has deep, long personal ties, 3) in 2011 Japan used its good offices to arrange the first meeting (at Narita Airport) between Philippines President Aquino and MILF Chairman (now Chief Minister of the Bangsamoro Transition Authority) Murad Ebrahim,  4) Japan is the only international partner with an advisor inside the office of the Chief Minister, 5) today Japan is the largest international donor in the Bangsamoro. These efforts stand in sharp contrast to U.S. efforts in Mindanao, which have been focused on counterterrorism rather than the peace process itself.Beyond contributions to peace, Japan’s support for the peace process is also viewed as a wellspring for broader Japan-Philippines relations for two primary reasons: 1)  before becoming President, Rodrigo Duterte, the first Philippines president from Mindanao, was very familiar with Japan’s support to the peace process, which contributed to Duterte’s positive approach to Japan during his presidency, 2)  the centrality of the conflict for the Armed Forces of the Philippines has exposed a generation of leaders to Japan’s positive contributions to peace.
  • Japan and the Philippines are grappling with similar threats of Chinese malign information operations that also directly impact the United States. From Manila’s perspective, it is engaged with China in a two-front contest in the South China Sea – on the water and in the information space. In a stark reversal from President Duterte’s approach, in which he sought to sweep China’s aggressive and dangerous actions against Philippines vessels under the rug, Marcos has undertaken a bold strategy that has been described as “assertive transparency” to show the Filipino people and the world exactly what China is doing.[15] This approach seeks to counter Chinese attempts to shape Philippines public attitudes through pervasive attempts in the information environment to raise doubts about Philippines interests in the South China Sea and the utility of its alliance ties with the United States.[16] Philippines officials are also concerned that China is seeking to sway opinion in communities that would host rotational U.S. military forces under the Enhanced Defense Cooperation Agreement.Japan is beginning to confront challenges that have strong echoes of what is happening in the Philippines. In numerous meetings, it was cited that Chinese information operations in Japan are most notably targeted at the people of Okinawa and seek to: 1) delegitimize the idea of Okinawa being historically part of Japan, 2) inflame opposition to U.S. military presence in Okinawa, and 3) drive divisions between Okinawa and Tokyo. In the last year, artificial intelligence is seen for the first time to be enabling sophisticated messaging in Japanese. Previously, Japanese was seen to be too complex for foreign malign actors to use with native Japanese speakers easily able to identify misinformation as well as scams.


In less than a year, the U.S.-Japan-Philippines triangle has taken shape remarkably quickly due to shared interests, outlooks, and geography. To sustain momentum, core priorities for tangible cooperation will need to be consolidated and new networks and structures will need to be put in place.

Structure and Networks

  • Government structures will naturally need to be developed to drive trilateral cooperation. While the three NSCs have to date driven much of early cooperation, the most practical format for regular trilateral meetings will be some combination of Foreign and Defense Ministry officials with other Interagency partners participating as appropriate. While the Philippines NSC is an operational, agency-like entity, the U.S. and Japanese NSCs are thinly staffed and less operational. It will also be important not to formalize the meetings at too high a level to ensure they are easy to schedule.Regular meetings across the three Interagencies will also begin to build interpersonal ties between key officials and build understanding of each countries’ systems. As in other trilateral arrangements, meetings will enable officials to better understand the legs of the triangle to which they are not party. For the United States, there will be much to be learned from the steadiness that has contributed to smooth Japan-Philippines relations. For the Philippines, first-hand insight into the U.S.-Japan alliance could prove valuable as the U.S.-Philippines alliance takes on more structure and depth.
  • Non-governmental forums to network experts from the three countries are needed to sustain relations, including during difficult times, and to be generators of new ideas. Trilateral track 1.5 and track two dialogues are a tried and true formula for generating ideas and building relationships and should be regularized. These dialogues should not solely be focused on immediate security issues and should become venues for broad strategic conversations on a wide range of issues. As the Philippines and the U.S.-Japan-Philippines triangle become increasingly important to the United States and Japan, organizations dedicated to U.S.-Japan relations should creatively find opportunities to connect experts from the three countries.
  • Quadrilateral U.S.-Japan-Philippines-Australia relations hold promise, but the view from Tokyo is it will be important to first institutionalize U.S.-Japan-Philippines trilateral cooperation. While attractive due to shared interests and outlooks among the four, the United States, Japan, and the Philippines should not allow the unwieldiness of scheduling and conducting quadrilateral meetings to slow down progress on a trilateral partnership that is currently ripe to deliver results. However, when opportunities present themselves, particularly on the sidelines of multilateral meetings, ad hoc quadrilateral opportunities should be seized to demonstrate an even broader alignment of views.

Focus Areas

  • Maritime security and broader defense cooperation will remain the single most natural and tangible area of cooperation for the three countries and is already underway through joint exercises and efforts to enhance the capacity of the Philippines Navy and Coast Guard. With Japan still maintaining significant post-war self-constraints on defense sales and assistance, there will be natural synergy between Japanese and U.S. assistance. After the signing of the Reciprocal Access Agreement, the three countries should also deepen coordination related to military construction in the Philippines to support implementation of EDCA and to bring Japan more closely into U.S. planning.
  • Countering Chinese disinformation and propaganda is a shared challenge that would benefit from the three parties sharing their own experiences and potential best practices. As U.S. allies, Japan and the Philippines are being targeted with similar messages. The Philippines has important, current information about Chinese tactics in the Philippines that would be useful to Japanese and American counterparts. This triangle of trusted, democratic partners also provides a venue for dialogue on government structures and laws that can help build resilience to this type of malign influence.
  • Supporting peace in Mindanao should be a strategic priority for all three countries because it is prerequisite for the AFP to truly pivot to a focus on territorial defense. While Japan is deeply engaged, the United States could do much more to support the new Bangsamoro government though technical support for delivery of government services and economic development projects to help deliver on public expectations for a peace dividend. Joint U.S.-Japan initiatives would be especially warmly received by the Bangsamoro government and public.

Mr. Brian Harding joined the U.S. Institute of Peace (USIP) in May 2020 as a senior expert and has led a major expansion of USIP’s programing in Southeast Asia and the Pacific Islands, including the launch of new country programs in the Philippines, Vietnam, and Papua New Guinea.  

USIP is a national, nonpartisan, independent institute, founded by the U.S. Congress, that works to prevent, mitigate, and resolve violent conflict abroad. USIP’s Philippines program works with the Philippines national government on a range of international security challenges and is deeply engaged in Mindanao supporting the implementation of the 2014 Comprehensive Agreement on the Bangsamoro.  

Prior to joining USIP, Mr. Harding was deputy director of the Southeast Asia program at the Center for Strategic and International Studies and director for East and Southeast Asia policy at the Center for American Progress.  

From 2009 to 2013, he served in the Office of the Secretary of Defense at the Pentagon as country director for Asian and Pacific security affairs where he managed U.S. defense relations with a range of U.S. partners including Indonesia, Singapore, and Australia.  


[1] Sharon Seah et al., “The State of Southeast Asia: 2023 Survey Report,” ASEAN Studies Centre, February 9, 2023,

[2] Bill Ide, “Duterte Announces Philippine ‘Separation’ from US,” Voice of America, October 20, 2016,

[3] “National Security Policy 2023-2028,” National Security Council, Government of the Philippines, August 2023,‌NSS_NSP/National_Security_Policy_Manual_FINAL_E-COPY_with_WATERMARK_140823.pdf.

[4] Renato Cruz De Castro, “The Marcos Administration’s Foreign Policy towards the Great Powers: Seeking the Elusive Balance in Dealing a Changing Indo-Pacific,” East Asian Policy 15, no.04 (October/December 2023) 95-115,‌S1793930523000314.

[5] “Philippines: Priority Areas,” Japan International Cooperation Agency, accessed January 2023,‌english/‌activities/‌‌activity_02.html.

[6] “Signing and Exchange of Notes for Official Security Assistance (OSA) to the Republic of the Philippines,” Ministry of Foreign Affairs of Japan, November 3, 2023,

[7] Rieko Miki, “Philippines buys Mitsubishi Electric radar in first defense deal,” Nikkei, March 27, 2020,‌International-relations/Philippines-buys-Mitsubishi-Electric-radar-in-first-defense-deal.

[8] “Joint Readout of Trilateral Meeting Between the National Security Advisors of the United States, Japan, and the Philippines,” the White House, June 16, 2023,

[9] “Secretary Blinken’s Meeting with Japanese Foreign Minister Kamikawa and Philippine Secretary of Foreign Affairs Manalo,” U.S. Department of State, September 22, 2023,

[10] Author’s discussion with former senior INDOPACOM official.

[11] Adrian Portugal and Martin Petty, “Philippines, Japan, U.S. hold first trilateral coast guard manoeuvres,” Reuters, June 6, 2023,

[12] Gregory B. Poling, Andreyka Natalegawa, and Danielle Fallin, “Building a US-Japan-Philippines Triad,” CSIS Briefs, Center for Strategic and International Studies, February 2023,‌VersionId=fXPcQHz5zxOLx3NHfE9QLjnk6o3ACBYR; Carl Baker and Jeffrey Ordaniel, “South China Sea, East China Sea, and the Emerging U.S.-Japan-Philippines Trilateral,” Issues & Insights, Pacific Forum, April 2023,‌‌/‌uploads‌/‌2023/04/‌Issues-and-Insights-Vol-23-CR1-1.pdf.

[13] Brian Harding and Haroro J. Ingram, “Bangsamoro Peace and the U.S.-Philippines Alliance,” Lawfare, September 11, 2022,

[14] Haroro J. Ingram, “The Cascading Risks of a Resurgent Islamic State in the Philippines,” United States Institute of Peace, January 9, 2024,

[15] Ray Powell and Benjamin Goirigolzarri, “Assertive Transparency: The Philippines’ Counter Gray Zone Innovation,” SeaLight, October 7, 2023,

[16] Pauline Macaraeg, “How pro-China propaganda is seeded online in the Philippines,” Rappler, November 1, 2023,‌newsbreak‌/investigative/ways-how-china-propaganda-seeded-online-philippines/.

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