Japan Troops Return to Philippines: Indo-Pacific Defence Shift

Japanese Troops Return to Philippine Soil After 81 Years, Signalling Strategic Shift

Next month will witness a historic moment as at least 1,000 Japanese armed combat troops set foot on Philippine soil for the first time in 81 years, since the end of World War II. This significant deployment, occurring as part of the joint Philippine-US Balikatan military training exercises, signifies a fundamental change in the Indo-Pacific security landscape. Experts note a transition away from the traditional “hub-and-spoke” strategy towards a more interconnected web of overlapping minilateral groupings, with the region increasingly viewed as a single, unified theatre of operations.

General Romeo Brawner Jr., Chief-of-Staff of the Armed Forces of the Philippines, underscored the profound importance of this return during a conference commemorating 70 years of diplomatic relations between Manila and Tokyo. He stated that the presence of Japanese combat troops marks a significant departure from the past, as such deployments had been prohibited in the Philippines since 1945.

The historical context is poignant: during Japan’s three-year occupation of the Philippines, an estimated half a million Filipinos lost their lives. Brawner acknowledged this painful past, highlighting that while the nations were once adversaries, they now stand on the same side. This collaborative spirit extends to joint defensive operations alongside the United States and Australia, forming a four-nation alliance.

The “One Theatre” Concept and Evolving Security Architecture

This evolving security paradigm was further institutionalised in December last year with the signing of an agreement by the armed forces of these four nations in California. This grouping has been informally dubbed “The Squad” by Pentagon officials. General Brawner indicated that this agreement serves as a foundation for numerous future activities, with potential expansion to include countries like South Korea and India.

He further revealed that he, along with former Japanese military counterpart General Yoshihide Yoshida, spearheaded the “One Theatre Concept.” This initiative, coined OCEAN (One Coordinative Effort Among Nations), aims to bolster security across the Indo-Pacific. OCEAN emphasizes a comprehensive and collective approach to defence, extending beyond military concerns to encompass energy and food security. Its scope includes safeguarding vital submarine cables, advancing artificial intelligence capabilities, and securing space and cyberspace.

“So now we try to fight in all domains, not just the traditional ground, air, and sea. We have non-traditional domains [such as] cyber, information, cognitive and space,” Brawner explained. He stressed the necessity of collaboration with international partners to rapidly develop the capabilities required to operate effectively across these diverse domains.

Retired navy rear admiral Rommel Jude Ong elaborated on the “One Theatre” concept, stating that it views the North China Sea, East China Sea, and South China Sea as interconnected. He argued that these bodies of water cannot be treated in isolation, as maritime vessels naturally traverse across perceived boundaries.

Japan’s Strategic Overhaul and Deepening Partnership with the Philippines

Analysts believe this strategic shift aligns with the strengthening ties between Japan and the Philippines, as well as Tokyo’s own reorientation of its military strategy in Asia. Ken Jimbo, a professor at Keio University specializing in Japanese security, noted that the Japan-Philippines relationship is becoming a cornerstone of the Indo-Pacific’s emerging security architecture. Both nations are committed to sustaining this momentum and addressing any existing discrepancies.

Jimbo highlighted Japan’s recent move towards a more expansive strategy focused on deterrence, resilience, and strategic partnerships. This includes enhancing its air and missile defence capabilities, fostering closer collaboration with allies and partners, and reinforcing its defence industrial and technological base. Consequently, Japan is emerging as a more potent security actor, contributing to regional stability through practical cooperation, institutional frameworks, and capacity-building support.

He outlined two key aspects of Japan’s evolving role:

• A more consequential provider of strategic public goods in the Indo-Pacific: This encompasses maritime security, capacity building, logistics, infrastructure support, and official security assistance.
• A more operational partner, extending beyond diplomatic engagements: Japan is increasingly involved in practical, on-the-ground security cooperation.

Jimbo cited specific examples of this deepening partnership:

• Reciprocal Access Agreement (RAA): Effective since September last year, this agreement facilitates the exchange of combat troops and joint war exercises between Japan and the Philippines.
• Acquisition and Cross-Servicing Agreement (ACSA): This military pact enables the exchange of supplies, fuel, and logistical services.
• Official Security Assistance (OSA): The Philippines has benefited from Japan’s OSA program, receiving significant military aid. As of February this year, this has included:
  • Coastal surveillance radar systems for the Philippine navy, valued at 600 million yen (approximately US$3.76 million).
  • Rigid-hulled inflatable boats (RHIBs) worth 1.2 billion yen.
  • An air surveillance radar system for the Philippine Air Force.
  • 900 million yen allocated for the construction of boat houses and slipways to support RHIB operations.

For the Philippines, Japan represents a partner that offers both strategic seriousness and political dependability. Tokyo’s support is perceived as stabilizing, rule-based, and increasingly tangible. This defence partnership is actively reshaping the Indo-Pacific security landscape, fostering a more networked regional order.

Jimbo explained that for a considerable period, Indo-Pacific security was primarily understood through bilateral security structures, often referred to as hub-and-spoke mechanisms. However, the current trend indicates a rise in overlapping partnerships among like-minded states, with Japan-Philippine cooperation being a crucial element of this transformation. This signifies a move towards a more horizontal, rather than strictly hierarchical, regional architecture.

The bilateral cooperation also bridges different security dimensions, including military access, logistics, maritime and domain awareness, and security assistance. This functional alignment, rather than mere symbolic solidarity, is what imbues the evolving architecture with significant importance.

Furthermore, the unity demonstrated by these nations carries broader implications. It signals to the region that middle powers and maritime states are not passive bystanders in strategic competition. Instead, they possess the agency to actively shape their environment through established rules, collaborative institutions, and coordinated capacity-building efforts.

Despite these advancements, Jimbo acknowledged that certain “gaps” persist. These include the pace of implementation, delays in defence industrial cooperation, and challenges in “cross-domain integration.” He emphasized that future regional security architecture will also be influenced by emerging factors such as cyberspace, undersea infrastructure, and critical technologies.