In January 2025, during his first visit to Indonesia as Japanese prime minister, Ishiba Shigeru announced that Japan would send two high-speed patrol vessels to Indonesia under its Official Security Assistance (OSA) programme. In the same month, the Indonesian Maritime Security Agency signed a contract to receive a new high-speed patrol vessel under Tokyo’s Official Development Assistance (ODA) programme. These marked the latest in a series of patrol-vessel transfers to Southeast Asian coastguards, as Japan seeks to accelerate maritime cooperation with Southeast Asian countries in response to the deteriorating security environment in the Indo-Pacific. The focal point of security threats in Southeast Asian waters has shifted from non-traditional areas such as terrorism and piracy, which dominated attention in the early 2000s, to the more traditional area of state-sponsored coercive actions, perpetrated by China over territorial claims in the South China Sea, from the 2010s. Over the past couple of decades, Tokyo has successfully cooperated with Southeast Asian coastal states to counter these threats, largely by helping to build up these states’ coastguard capacities under its ODA programme. While Tokyo’s deployment of a civilian coastguard rather than naval forces results from constraints imposed by the ‘renunciation of war’ in Article 9 of the Japanese constitution, the recent development of Chinese state-backed militia operations will likely make coastguards the de facto naval front line for territorial defence in Southeast Asia over the longer term.
Japan’s maritime cooperation in Southeast Asia
