Japan–Philippines Acquisition and Cross-Servicing Agreement: Boosting Defence ties

Introduction

The strategic landscape of the Indo-Pacific has been transforming in recent years due to intensifying great-power competition, China’s expansionist behaviour, and challenges to the rules-based international order. These shifts are most evident in the East and South China Seas, where coercive maritime activities and grey-zone operations have increased insecurity among regional states. In this evolving security environment, middle powers are seeking reliable defence partnerships to protect their sovereignty, enhance deterrence and regional stability. Japan and the Philippines, both maritime nations and heavily reliant on secure sea lines of communication, are at the forefront of such regional dynamics.

Japan and the Philippines have been steadily strengthening their defence partnership, reflecting broader shifts in the Indo-Pacific security environment. Their bilateral ties are now expanding into the strategic domain, along with economic cooperation and development assistance, further underscoring both nations’ adaptation to growing regional uncertainties. Defence ties between Japan and the Philippines are driven by mutual concerns about China’s expansionist behaviour, maritime security, and the need to uphold and preserve a rules-based international order in the Indo-Pacific.

In this context, the Japan–Philippines Acquisition and Cross-Servicing Agreement (ACSA) emerges as a critical outcome of this strategic convergence. Both countries signed the ACSA, a military logistics pact, on 15 January 2026. This occurred during Japan’s Foreign Minister Toshimitsu Motegi’s visit to the Philippines.^[1] The agreement enables the Japanese Self-Defence Forces (SDF) and the Armed Forces of the Philippines (AFP) to exchange supplies, fuel and logistical services during joint military exercises, humanitarian operations, and potential contingencies. This deal is also in line with the landmark Reciprocal Access Agreement (RAA) between the two countries, signed in July 2024, which permits the deployment of forces on each other’s territory for combat training and disaster response.^[2] These agreements reflect an institutionalised security partnership in a shifting Indo-Pacific, coinciding with the 70^th anniversary of the establishment of diplomatic relations between Japan and the Philippines this year.

Strategic Context

Japan has been facing mounting pressure in the East China Sea, where China’s Coast Guard (CCG) vessels frequently operate near the Senkaku Islands, uninhabited islets administered by Tokyo and claimed by Beijing. China’s encounters have at times prompted Japan to scramble fighter jets, underscoring the severity of the confrontations. At the same time, the Philippines has been in an increasingly tense stand-off with China in the South China Sea. Beijing’s maritime aggression and grey-zone coercion have intensified over time, as seen by the CCG’s nearly daily presence within the Philippines’ Exclusive Economic Zone (EEZ). Chinese maritime agencies are known to obstruct fishing and undertake resource exploitation, which often leads to vessel collisions in the South China Sea. These parallel challenges and mutual concerns have aligned the strategic priorities of Japan and the Philippines, further deepening their security partnership.

Japan’s shift towards more proactive security engagement and defence assistance has expanded its role from being only an economic partner to a security provider. Japan’s pacifist constitution has restricted its military capabilities since the post-Second World War period, limiting Japan’s engagement in defence partnerships. Under Shinzo Abe’s administration, Japan witnessed a turning point in its security policy with a significant focus on proactive contribution to peace and eventual re-interpretation of Article 9 of the Constitution in 2015, which allowed for collective self-defence and expanded the role of Japan’s SDF to provide logistical support and participate more actively in international security operations.^[3]

The Japanese government chose to provide the Philippines with 10 patrol boats to improve its capabilities after the Philippines lost control of Scarborough Shoal in 2012.^[4] Japan’s decision reflected concern about the shifting balance of power in the South China Sea and its implications for freedom of navigation. Since 2012, there have been more frequent high-level discussions between the two nations, demonstrating the expanding nature of security cooperation. In April 2022, high-level meetings between the two countries led to the establishment of a 2+2 ministerial framework, under which the foreign and defence ministers meet to discuss strategic matters.^[5] The most recent and significant effort by Japan to enhance its defence support is the establishment of the Overseas Security Assistance (OSA) Programme in April 2023.^[6] The Philippines was the first recipient of Japan’s OSA and received a coastal radar system under the new mechanism.^[7]

Recalibrating Regional Security Architecture

Together, the ACSA and the RAA expand boots-on-the-ground operational access, while the former further institutionalises logistical interoperability. In addition to ACSA, the Philippines Foreign Affairs Secretary, Theresa Lazaro and Japan’s Foreign Minister, Toshimitsu Motegi, signed two other bilateral agreements: the 900 million Yen Exchange of Notes for OSA.^[8] The Philippines lies along key sea lanes, including the South China Sea and the Luzon Strait, which play a significant role in regional security. Under the OSA programme, the construction of boathouses and slipways for the Philippine Navy’s rigid-hulled inflatable boats is the first infrastructure project.^[9] The project is expected to enhance the Philippine Navy’s marine domain awareness and surveillance capabilities.

Another agreement relates to the 1.63 billion Yen Exchange of Notes for Grant Aid for the Establishment of Wireless Broadband Connectivity for Basilan, Sulu and Tawi-Tawi.^[10] These provinces are in remote areas of Mindanao and lag in socio-economic infrastructure development due to security and geographical conditions. Japan has long supported peace, development and growth in Mindanao. By building communication infrastructure (microwave radio transmission devices and IT equipment) for network-based public services and other facilities in the area, the project seeks to close the digital divide and advance the socio-economic development of the Philippines.

Beyond the functional utility, the ACSA has broader strategic significance. It signals Japan’s security engagement with Southeast Asia as part of its ‘Free and Open Indo-Pacific’ (FOIP) vision, while also reflecting the Philippines’ efforts to diversify its defence partnerships amid an uncertain security environment. Moreover, the agreement is an expression of shared strategic intent that reinforces trust, contributes significantly to regional deterrence and also strengthens the networked security architecture of the Indo-Pacific.

Regional and Strategic Implications

The ACSA and RAA have enabled logistics interoperability, capacity-building and deeper operational cooperation. The Philippines also relies on the Mutual Defence Treaty with the US for security guarantees. The expanding strategic relationship with Tokyo acts like a complementary pillar of deterrence and enhances operational readiness of the AFP.

The strengthening of defence ties between Japan and the Philippines, two US allies, suggests that a new security network centred on the US has emerged alongside existing minilateral organisations such as the QUAD. In Indo-Pacific geopolitics, the security alliance between the Philippines and Japan has developed gradually. It has significantly strengthened Manila’s diplomatic anchor and further integrated it into the current network of US-led alliances in the region. Both Lazaro and Motegi reaffirmed their commitment to bolstering the trilateral partnership among Japan, the Philippines and the US.^[11]

Such alliances may send a strong signal to China that the countries are firm in upholding the rules-based maritime order. Moreover, there are converging interests and mutual concerns among India, Japan and the Philippines. These countries have been seeking ways to cooperate with other middle powers to counter Chinese influence. Such minilateral and trilateral partnerships can go beyond bilateral ties and build concrete alliances with like-minded countries.

Furthermore, Japan–Philippines defence ties have humanitarian implications that extend beyond conventional security concerns. Since both nations are vulnerable to natural disasters, enhanced military cooperation facilitates coordination of relief and humanitarian efforts. In this way, defence cooperation encompasses resilience and quick response in addition to deterrence.

However, the deepening of defence ties between the two nations also brings sensitivities and challenges. Such pacts and agreements, as evidenced by history, carry the risk of drawing the Philippines into great-power rivalries. This is a legitimate concern, mainly due to Manila’s historically cautious foreign policy and strong ties across Asia. Secondly, there are concerns that Japan’s pacifist principles and constitutional constraints may limit its actions. At the same time, critics in Japan argue that overt involvement in defence-related activities, such as providing military equipment to other countries through OSA, could undermine these pacifist ideals and risk Japan becoming involved in international conflicts.^[12]

Philippine policymakers on their part would strive to balance security cooperation with concerns about regional diplomacy and sovereignty, while Japan would be expected to remain cautious about provoking tensions. Japan’s support of logistical coordination and advanced maritime capabilities enables the Philippines to strengthen its own defence readiness without provoking escalation.

Conclusion

The Japan–Philippines ACSA is a symbol of strategic trust and a step towards military interoperability. China’s assertiveness and the security challenges faced by both countries are a major driver of this convergence. From the Philippines’ perspective, closer defence ties with Japan represent a pragmatic shift to diversify its security partnerships. Japan’s approach represents an evolution in its security policy and has expanded the scope of its defence engagement. The ACSA would also enhance Japan’s regional influence and prepare both countries to address the threats.

The deepening of defence ties between Japan and the Philippines reflects a new trend in the Indo-Pacific region, where middle powers are working together to navigate a complex regional security environment. These ties are being built through agreements, exercises, shared norms and other practical cooperation, which may prove effective in maintaining peace over time amid the region’s changing security architecture.

Views expressed are of the author and do not necessarily reflect the views of the Manohar Parrikar IDSA or of the Government of India.

^[1] “Signing of the Agreement between the Government of Japan and the Government of the Republic of the Philippines Concerning Reciprocal Provision of Supplies and Services between the Self-Defense Forces of Japan and the Armed Forces of the Philippines”, Ministry of Foreign Affairs (MOFA), Japan, 15 January 2026.

^[2] Aries A. Arugay and Mico A. Galang, “The Japan-Philippines Reciprocal Access Agreement: Complementing and Cementing the Hub-and-Spokes System”, ISEAS-Yusof Ishak Institute, 13 September 2024.

^[3] Sheila A. Smith, “Re-interpreting Japan’s Constitution”, Council on Foreign Relations, 2 July 2014.

^[4] Renato Cruz De Castro, “Facing Up to China’s Realpolitik Approach in the South China Sea Dispute: The Case of the 2012 Scarborough Shoal Stand-off and Its Aftermath”, Journal of Asian Security and International Affairs, July 2016.

^[5] “First Japan-Philippines Foreign and Defense Ministerial Meeting (“2+2”)”, MOFA, Japan, 9 April 2022.

^[6] Ippeita Nishida, “Outstanding Issues for Official Security Assistance (OSA) and its Strategic Utilization”, Sasakawa Peace Foundation, 8 November 2023.

^[7] Ibid.

^[8] “Signing and Exchanging of Notes for Official Security Assistance (OSA) FY2025 Project to the Republic of the Philippines”, MOFA, Japan, 15 January 2026.

^[9] Ibid.

^[10] “Signing and Exchange of Notes Concerning the Grant Assistance “Economic and Social Development Program” to the Republic of the Philippines (Provision of Wireless Communication Equipment)”, MOFA, Japan, 15 January 2026.

^[11] Joyce Ann L. Rocamora, “Japan, PH Want Stronger Ties with US Amid Complex Reg’l Landscape”, Philippine News Agency, 15 January 2026.

^[12]  Ippeita Nishida, “Outstanding Issues for Official Security Assistance (OSA) and its Strategic Utilization”, no. 6.

Keywords : Japan, Philippines