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Japan is advancing a layered maritime security strategy in the Indo-Pacific by combining defence cooperation, capacity building, and strategic financing with key partners such as India, Indonesia, and Australia.
This article is part of the series—Jakarta Edit 2025
As tensions in the Indo-Pacific continue to intensify — owing to growing US-China rivalry, grey-zone tactics, and frequent contestation over sea lanes — Japan is shaping a layered maritime strategy aligned with its strategic imperatives. Rather than a singular or reactive posture, this evolving approach integrates defence cooperation, capacity building, and strategic financing. In collaboration with partners such as India, Indonesia, and Australia, Japan seeks to enhance operational readiness and contribute to a more resilient maritime security environment.
This multi-track strategy reflects Japan’s intention to uphold a rules-based order, an essential prerequisite for a free and open Indo-Pacific, while mitigating strategic risks in an increasingly fluid and multipolar environment.
At the core of Japan’s maritime security lies its bilateral alliance with the United States, which underpins deterrence and stability in the region surrounding the Japanese archipelago. Yet, in recent years, Japan has significantly widened its defence partnerships beyond this axis. Through joint naval exercises and strategic dialogues, Tokyo has forged practical maritime coalitions with India, Australia, and increasingly, Indonesia.
At the core of Japan’s maritime security lies its bilateral alliance with the United States, which underpins deterrence and stability in the region surrounding the Japanese archipelago. Yet, in recent years, Japan has significantly widened its defence partnerships beyond this axis.
The Malabar Exercise, now a quadrilateral naval drill involving the United States, Japan, India, and Australia, has become a symbol of operational convergence among maritime democracies. Japan’s active engagement in such exercises reflects a conscious effort to build interoperable coalitions, not as fixed alliances, but as flexible, issue-based alignments.
In Southeast Asia, Japan’s cooperation with Indonesia has grown in both scale and sophistication. Participation in exercises such as the Super Garuda Shield and joint patrol initiatives illustrates Tokyo’s willingness to integrate itself into the regional security fabric.
These defence initiatives are driven by the recognition that no single actor can unilaterally secure sea lines of communication (SLOCs) or respond to the range of threats — from freedom of navigation challenges to grey-zone activities and maritime terrorism — that now define the Indo-Pacific maritime domain.
Recognising that durable maritime security requires more than deterrence, Japan has made capacity building a central pillar of its Indo-Pacific strategy. Nowhere is this more evident than in its engagement with Southeast Asia’s littoral states.
Through the Japan Maritime Self-Defence Force and the Japan Coast Guard, Tokyo has supplied partner nations with patrol vessels, surveillance systems, radar installations, and technical training. The provision of coast guard vessels to the Philippines and Vietnam, as well as maritime surveillance capabilities to Indonesia, has enhanced these nations’ ability to monitor and protect their maritime domains.
Importantly, Japan’s capacity building is not framed in zero-sum terms. Tokyo supports regional autonomy and resilience, not alignment. With Indonesia positioning itself as a ‘Global Maritime Fulcrum’ (GMF), Japan’s contribution to maritime domain awareness, officer training, and joint exercises is enabling Jakarta to better defend its vast archipelagic waters.
Japan’s capacity building is not framed in zero-sum terms. Tokyo supports regional autonomy and resilience, not alignment.
This emphasis on empowerment over dependence marks a distinct approach that strengthens regional norms without replicating alliance-like structures.
A recent yet transformative dimension of Japan’s maritime strategy is its utilisation of strategic finance to align economic instruments with security goals. In 2023, Japan institutionalised the Official Security Assistance (OSA) framework — an initiative that transforms Tokyo’s overseas support from purely developmental to strategic domains.
The OSA has already facilitated the provision of high-speed patrol vessels to Indonesia, and more broadly allows Japan to fund infrastructure, equipment, and training projects that enhance maritime security across the Indo-Pacific. This development signals a recalibration of Japan’s economic statecraft, one that prioritises regional security resilience.
Moreover, Japan is exploring naval maintenance, repair, and overhaul partnerships with Southeast Asian shipyards. By collaborating on the upkeep and lifecycle management of defence platforms, Tokyo is helping partner states reduce reliance on extra-regional suppliers, lower operational costs, and build indigenous industrial capacity. Japan’s support for expanded US naval repair capacities in the region further reinforces this supply chain resilience.
A recent yet transformative dimension of Japan’s maritime strategy is its utilisation of strategic finance to align economic instruments with security goals. In 2023, Japan institutionalised the Official Security Assistance (OSA) framework — an initiative that transforms Tokyo’s overseas support from purely developmental to strategic domains.
These financing mechanisms also extend to dual-use maritime infrastructure. Japan has partnered with India on smart island and green port initiatives in the Andaman and Nicobar Islands, aiming to enhance digital infrastructure, renewable energy, and disaster resilience, with co-benefits for maritime security. Similar cooperation with Indonesia’s outer islands supports logistical diversification and strategic redundancy across the Indo-Pacific.
In a time of growing uncertainty, Japan’s layered approach to maritime security reflects an effort to strengthen regional resilience through practical cooperation. By combining elements of deterrence, capacity building, and strategic financing, Japan is supporting its partners in responding to diverse maritime challenges while maintaining space for independent decision-making. Cooperation with India, Indonesia, and Australia demonstrates that maritime security in the Indo-Pacific can be advanced not only through formal alliances but also through more flexible and issue-based arrangements rooted in shared interests.
As competition in the Indo-Pacific becomes increasingly complex, this type of layered cooperation may serve as a useful model — not as a fixed system, but as an evolving framework that helps manage risks and reinforce stability through sustained engagement.
Ken Jimbo is the Managing Director of the International House of Japan and a Professor at Keio University, Japan.
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Ken Jimbo is the Managing Director of the International House of Japan and a Professor at Keio University, Japan. ...
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