As Manila and Tokyo mark 70 years of diplomatic relations, their expanding defence partnership is emerging as a central pillar of Indo-Pacific stability and a key driver of a rules-based maritime order
Philippines-Japan relations have markedly deepened over the past few years, emerging as one of the most consequential partnerships in Manila’s broader effort to diversify its security and defence engagements with like-minded states. This evolution has been particularly timely, unfolding against a backdrop of intensifying maritime tensions, persistent grey-zone challenges, and growing uncertainty in the regional security environment. All of these underscore the need for stronger, more enduring strategic partnerships.
The recent signing and entry into force of the Japan-Philippines Reciprocal Access Agreement (RAA) stand out as a key development, enabling the two countries’ armed forces to operate on each other’s territory with greater legal, administrative, and operational clarity. By establishing clear rules governing the entry, presence, and activities of forces, the RAA strengthens interoperability and enables more sustained joint exercises, training activities, and operational coordination between the Armed Forces of the Philippines (AFP) and the Japan Self-Defense Forces (JSDF).
The Philippines and Japan signed ACSA, a development widely seen as complementing—and operationalising—the RAA. While the RAA provides the legal foundation for the presence and movement of forces, the ACSA supplies the logistical backbone that allows such cooperation to be sustained in practice.
There is little indication that the momentum created by the RAA will slow in the near term. On the contrary, it continues to build. This is demonstrated by the recent signing of the Acquisition and Cross-Servicing Agreement (ACSA) and the steady expansion of Japan’s Official Security Assistance (OSA) to the Philippines. Most importantly, Prime Minister Sanae Takaichi, at the helm in Tokyo after securing a historic win in the February snap elections, is positioned to pursue her security agenda with greater support.
In January 2026, the Philippines and Japan signed ACSA, a development widely seen as complementing—and operationalising—the RAA. While the RAA provides the legal foundation for the presence and movement of forces, the ACSA supplies the logistical backbone that allows such cooperation to be sustained in practice.
The ACSA establishes a framework for the reciprocal provision of supplies and services between the AFP and the JSDF. These include fuel, food, water, transportation (including airlift), medical services, communications services, spare parts, repair and maintenance services, airport and seaport services, and ammunition—while explicitly excluding the transfer of weapons.
In practical terms, the ACSA enables both forces to operate together with greater speed and efficiency, particularly in crisis or contingency scenarios. At the same time, its scope is deliberately limited: the agreement is intended to facilitate logistical support and sustainment, not to provide capability enhancement or force modernisation. It does not, by design, address gaps in equipment, infrastructure, or long-term capacity building. This is precisely why Japan’s Official Security Assistance (OSA) to the Philippines has emerged as an equally important—if not indispensable—pillar of bilateral defence cooperation, complementing the ACSA by directly strengthening the Philippines’ security and deterrence capabilities.
The Philippines stands as the first and only multi-year recipient of OSA, a programme that represents a fundamental shift in Japan’s approach to security cooperation. Distinct from Official Development Assistance, OSA is designed to enhance the security and deterrence capabilities of partner countries, as introduced in its 2022 National Security Strategy.
The Philippines stands as the first and only multi-year recipient of OSA, a programme that represents a fundamental shift in Japan’s approach to security cooperation.
The trajectory of OSA to the Philippines illustrates both scale and intent. In fiscal year 2023, Japan provided ¥600 million (approximately PHP228 million) for the provision of coastal radar systems, directly enhancing the Philippines’ maritime domain awareness at a time of increasing pressure in the West Philippine Sea. In fiscal year 2024, this support expanded significantly, with an additional ¥1.6 billion (approximately PHP611 million) allocated for defence equipment, including rigid-hulled inflatable boats (RHIBs) and coastal radar systems for the Philippine Navy, as well as air surveillance radar–related equipment for the Philippine Air Force.
Alongside the signing of the ACSA, Japan committed an additional ¥900 million (approximately PHP341 million) for fiscal year 2025 in support of Manila’s efforts to modernise the capabilities of the AFP. These funds are intended for the construction of boathouses and slipways for RHIBs for the Philippine Navy. This project, aimed at enhancing the Philippine Navy’s maritime domain awareness and surveillance capabilities, is Japan’s first infrastructure project under its OSA programme.
Beyond existing agreements and ongoing assistance, Philippines-Japan defence cooperation continues to deepen through the increasing frequency of bilateral maritime cooperative activities, as well as Japan’s continued participation in multilateral exercises such as Balikatan.
Against this backdrop of deepening institutional and operational cooperation, political signalling from Tokyo has reinforced the trajectory of Philippines–Japan relations. Prime Minister Sanae Takaichi articulated early and clearly the strategic importance she attaches to the Philippines, explicitly citing the country in her first policy speech in October following her inauguration, with President Ferdinand Marcos Jr. becoming the first ASEAN leader to engage with her in person after she assumed office. These gestures were not merely symbolic; they conveyed deliberate prioritisation and reflected a strong alignment with Manila’s emphasis on maritime security, adherence to international law, and resistance to coercive behaviour in the maritime domain.
Looking ahead, as the Philippines and Japan mark 70 years of diplomatic relations, defence and security cooperation stands as one of the most dynamic pillars of that relationship.
This convergence at the leadership level mirrors a broader alignment in strategic outlook and threat perception, positioning a deepening Japan-Philippines security partnership to meaningfully shape Indo-Pacific regional dynamics. The partnership signals a growing commitment by like-minded states to uphold a rules-based order and to deter unilateral actions that seek to alter the status quo by force or coercion, consistent with the shared vision of a Free and Open Indo-Pacific. This cooperation strengthens regional stability — not through confrontation, but through enhanced collective deterrence.
Equally significant is how this bilateral partnership is embedded within a wider commitment to multilateralism. Japan and the Philippines view their security cooperation not as an exclusive arrangement, but as a platform for engaging other like-minded partners. Within this broader approach, mechanisms such as trilateral cooperation with the United States serve to deepen coordination and align responses to shared challenges.
Looking ahead, as the Philippines and Japan mark 70 years of diplomatic relations, defence and security cooperation stands as one of the most dynamic pillars of that relationship. Anchored in robust legal frameworks, reinforced by tangible capability support, and complemented by even deeper economic cooperation, this partnership has emerged as one of the most strategically significant relationships in the region. With momentum firmly on their side, this partnership is poised not only to endure but to play an increasingly influential role in shaping the Indo-Pacific’s security architecture in the years ahead.
Victor Andres “Dindo” Manhit is the President of the think tank Stratbase Institute.
Linar-Mae Orbista is the Program and Research Manager for Defense and Security at the think tank Stratbase Institute.
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Victor Andres “Dindo” Manhit is the President of the think tank Stratbase Institute. ...
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Linar-Mae Orbista is the Program and Research Manager for Defense and Security at the think tank Stratbase Institute. ...
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