U.S.-Japan-Philippines Trilateral Cooperation

The United States and Japan are already among the Philippines’ top trading partners, but there are opportunities to enhance trade and investment ties in energy, infrastructure, telecommunications, and critical minerals. On July 10, 2025, Secretary of State Marco Rubio met with his counterparts, Philippine Secretary of Foreign Affairs Maria Theresa Lazaro and then–Japanese Foreign Minister Iwaya Takeshi, in Kuala Lumpur, Malaysia, and advanced plans to develop the Luzon Economic Corridor, an initiative that was launched in 2024.³ The Luzon Economic Corridor is aimed at enhancing connectivity and port and infrastructure development across Luzon, which is only about 160 miles from Taiwan and is the largest and most populated island of the Philippine archipelago.

At their July 2025 meeting, the three foreign ministers also highlighted critical minerals as a key area for future cooperation. The Philippines has substantial critical mineral reserves and could play a role in helping to reduce global dependence on China. However, at present the PRC dominates the Philippine nickel supply chain. It will take time for the Philippines to shift its reliance on PRC supply chains that access its nickel reserves and for Manila to attract Western private sector investment into extracting and processing its critical minerals.⁴

While the Trump administration has so far demonstrated interest in deepening U.S.-Japan-Philippines trilateral cooperation, Trump’s unpredictable approach to foreign policy—especially regarding U.S. relations with China—leaves doubt about his continued support for a trilateral platform that China views as threatening to its own security interests. Trump could, for example, agree to back away from the trilateral partnership if he thinks doing so might bring PRC concessions on trade issues.

However, given the Trump administration’s goal, as laid out in the 2026 National Defense Strategy, to deal effectively with the increasing security challenges in the First Island Chain, particularly China’s military aggression against Taiwan and gray zone activity in the South and East China Seas, the United States should continue to invest in trilateral cooperation with Japan and the Philippines.⁵ Enhancing trilateral diplomatic, military, and economic collaboration will demonstrate that the three countries are united in their opposition to PRC acts of coercion and intimidation. Furthermore, the three nations’ increased coordination on military training, maritime patrolling, intelligence sharing, infrastructure development, and logistics will better prepare them for a potential military contingency in the region. Finally, the U.S.-Japan-Philippines trilateral partnership can lay the foundation for an expanded semiformal network of security relationships that enhances U.S. deterrence posture in the Indo-Pacific. Pursuing the following policy recommendations will help the three nations achieve these goals.

Summary of Recommendations

Security and Defense Cooperation

The United States, Japan, and the Philippines should deepen and institutionalize their trilateral cooperation to strengthen deterrence against PRC threats to Taiwan and in the South and East China Seas. The three countries should hold regular leader-level summits and establish a dedicated senior officials’ process to streamline strategic planning, synchronize investments, and minimize bureaucratic friction and establish a military-to-military mechanism to strengthen joint operational planning, improve information sharing, and coordinate joint training exercises.⁶

Japan and the Philippines should conclude a bilateral General Security of Military Information Agreement (GSOMIA) as soon as possible to allow the three countries to share information and improve trilateral interoperability. Tokyo and Manila should build on the momentum of having recently signed two other military agreements—a Reciprocal Access Agreement and an Acquisition and Cross-Servicing Agreement—to expeditiously conclude a GSOMIA.

The United States should rapidly appropriate and deploy greater resources to improve the development of infrastructure at U.S. Enhanced Defense Cooperation Agreement (EDCA) sites in the Philippines. Increased U.S. spending to support EDCA site construction is necessary to ensure operational effectiveness and sustained Philippine domestic support for a robust U.S. forward posture in the First Island Chain.

Japan should focus a portion of its increased military aid to the Philippines on supporting the development of infrastructure at U.S. EDCA sites in the Philippines. While so far Japan has used its Official Security Assistance (OSA) to the Philippines to fund radar systems, patrol boats, training aircraft, and most recently naval infrastructure, it should use OSA and consider reforms to allow for the provision of Official Development Assistance to fund infrastructure projects at EDCA sites, which would assist in trilateral humanitarian assistance and disaster relief efforts.

The United States, Japan, and the Philippines should integrate their foreign national evacuation plans to enhance regional preparedness for a Taiwan contingency. Building upon each nation’s independent initiatives, trilateral cooperation should leverage existing capabilities to operationally and logistically prepare for such a crisis. If willing, Taiwan should be included in these discussions as much as possible.

The United States, Japan, and the Philippines should initiate a dedicated trilateral effort to significantly enhance naval maintenance, repair, and overhaul capabilities at Subic Bay, transforming it into a resilient regional hub. This cooperation would enable rapid repairs, maintenance, and surge capacity during crises, reducing dependence on distant U.S. and Japanese shipyards and improving regional stability.

The United States, the Philippines, and Japan should shift from episodic exercises to a persistent, trilateral sea denial posture across the Luzon Strait. The United States should permanently deploy a mix of ground-based medium- and long-range precision fires at EDCA sites in northern Luzon and in Batanes, subject to Philippine government approval. These deployments, paired with Japan’s build-out of coastal missiles, radars, ammunition sites, and electronic warfare across the Ryukyu and Kyushu Islands, would enable the partners to hold at risk People’s Liberation Army assets operating north and south of Taiwan.⁷

Economic and Diplomatic Cooperation

The United States and Japan should work together to leverage the Philippines’ potential in critical minerals and rare-earth elements to reduce dependency on China. This would require conducting feasibility studies and providing incentives to the private sector to invest in the exploration, extraction, and development of these valuable resources.

The United States, Japan, and the Philippines should pool resources and coordinate investments to diversify subsea cable infrastructure and improve maritime monitoring. Together, they should lease cable repair ships, streamline regulatory processes to accelerate subsea cable deployments, and diversify cable landing station locations on the Philippines’ eastern coast away from contentious areas, as well as establish joint real-time maritime monitoring mechanisms and compile a shared database documenting cable-cutting incidents to enhance regional responses.

Introduction

The United States, Japan, and the Philippines face significant security challenges from the People’s Republic of China (PRC), whose aggressive military expansion and coercive maritime tactics have significantly heightened tensions throughout the Pacific. Beijing’s revisionist designs—from the Senkakus to the South China Sea—pose a clear and present danger to the safety and security of two core American allies, Japan and the Philippines.

In 2025, the People’s Liberation Army (PLA) conducted a record 163 operations in the South China Sea, including 55 live-fire drills, and doubled its presence around Scarborough Shoal.⁸ PLA vessels conducted 111 voyages in Japanese waters in 2025, including operations with its aircraft carriers, cruisers, and destroyers, and ordered 17 transits of the Osumi Strait near the new Japan Air Self-Defense Force base on Mageshima Island.⁹ These increased incursions, as well as collisions with Philippine coast guard vessels and radar lock-ons targeting Japanese fighter planes, underscore the urgency for a stronger, more integrated and comprehensive trilateral approach to effectively deter PRC aggression across the First Island Chain.¹⁰

Although the United States has historically maintained robust relationships through its bilateral alliances with Japan and the Philippines, PRC provocations have made trilateral cooperation more urgent. The first-ever leader-level U.S.-Japan-Philippines summit in April 2024 marked a new strategic consensus among the three countries—demonstrating a shared commitment to collective defense, economic engagement, and humanitarian cooperation.

The year 2026 marks a significant milestone year for U.S.-Japan-Philippines relations: 80 years of U.S.-Philippines diplomatic ties, the 75th anniversary of the U.S.-Philippines Mutual Defense Treaty and the signing of the original U.S.-Japan Security Treaty, 70 years of Japan-Philippines diplomatic ties, and the 10th anniversary of the landmark UN Convention on the Law of the Sea ruling affirming Philippine maritime claims.¹¹ In this milestone year, this report assesses the recent achievements and the current trajectory of trilateral cooperation and identifies areas requiring further collaboration.

The report begins by outlining the shared strategic rationale driving closer trilateral engagement, highlighting common security interests among the three nations. Subsequent sections detail recent advancements in defense and economic cooperation, emphasizing key developments such as Japan’s enhanced military assistance to the Philippines, the expansion of the Enhanced Defense Cooperation Agreement (EDCA), the implementation of the Japan-Philippines Reciprocal Access Agreement (RAA), significant U.S. infrastructure investments at strategic locations such as Subic Bay, and the establishment of the Luzon Economic Corridor. The report also addresses potential obstacles to trilateral cooperation, including President Donald Trump’s transactional approach to alliances, his efforts to gain trade concessions from China, and domestic political constraints within the Philippines in the lead-up to the Philippine presidential election in 2028.

Finally, the report proposes recommendations for policymakers designed to deepen trilateral cooperation by enhancing military interoperability, improving infrastructure resilience, and strengthening economic security. Through proactive coordination and strategic investments, the United States, Japan, and the Philippines can collectively reinforce regional stability. The strategic geography of Japan and the Philippines as part of the First Island Chain positions these nations as essential partners for the United States in maintaining a credible deterrence posture around Taiwan and within the contested waters of the South and East China Seas. Thus, this trilateral partnership forms the foundation of a comprehensive Indo-Pacific deterrence strategy.