TOKYO - Japan has been increasingly expanding security cooperation with Southeast Asian nations in recent years, providing defense equipment to bolster their capabilities amid China's growing assertiveness in the Indo-Pacific region.
But analysts caution against assuming that defense cooperation will automatically translate into strategic alignment, noting that national priorities vary widely across the region.
The Japanese government views the current international situation as "the most severe and complex security environment" since World War II and has sought to strengthen cooperation with like-minded partner nations to maintain a free and open Indo-Pacific.
A key pillar of that effort is the official security assistance framework launched in 2023, a grant assistance program under which Japan provides defense-related equipment and supplies to partner countries.
The program is intended to enhance the security and deterrence capabilities of like-minded countries, while helping smaller and middle-power nations strengthen their self-reliance and defense capabilities.
A senior Foreign Ministry official described the program as a tool to "broaden the scope" of Japan's security cooperation.
The number of recipient countries is expected to expand to at least 12 in the current fiscal year through March 2027, up from eight in fiscal 2025, with its budget more than doubling to approximately 18.1 billion yen ($114 million).
"What is significant is that (the security assistance program) has made it possible for us, the Foreign Ministry, to now have a direct channel to communicate with the militaries of other countries," another official of the ministry said.
While such communication was not entirely absent before, the main channel for negotiations had essentially been the official development assistance framework, which focuses on economic and social development, the official explained.
Japan plans to continue expanding the program to more countries, as well as provide more sophisticated and specialized equipment to those with which cooperation is already well established, officials said.
For decades, Japan maintained strict restrictions on defense equipment exports under its postwar pacifist policy. Transfers of finished equipment were largely limited to five noncombat categories -- rescue, transport, warning, surveillance and minesweeping.
But under Prime Minister Sanae Takaichi, Japan revised the three principles on transfer of defense equipment and technology and related operational guidelines in April, removing the five-category limitation in a significant shift in its defense policy.
Exports of lethal equipment, including destroyers and missiles, are now permitted but, in principle, only to countries that have concluded an accord concerning the transfer of defense equipment and technology with Japan, which requires appropriate safeguards for classified information and equipment management.
The Philippines, for example, is a relatively close security partner as the two countries share concerns about developments in the South China Sea, where Philippine and Chinese vessels have repeatedly clashed over disputed territory.
Through the security assistance program, Japan has sought to improve the Philippines' maritime security capabilities and strengthen its ability to monitor activities in waters surrounding the country, such as providing the Philippine Navy with defense radars, and assistance to construct boathouses and slipways for rigid-hulled inflatable boats.
Separate from the grant assistance program, the two countries have also reached a broad agreement for Tokyo to transfer five soon-to-be-retired Abukuma-class destroyers to Manila.
Japan's Defense Ministry positions the transfer of defense equipment and technology, including destroyers, as a "key policy instrument" to ensure peace and stability in the Indo-Pacific region, based on the National Security Strategy announced in 2022.
Similarly, Japan and Indonesia are discussing the possible transfer of the Maritime Self-Defense Force's Asagiri-class destroyers after they are decommissioned, as part of broader efforts to deepen bilateral defense ties. Their defense ministers agreed in June to launch talks on the matter.
Not all of Japan's partners, however, share the same strategic outlook. In the case of Indonesia, while Jakarta has deepened defense ties with Tokyo, it has simultaneously strengthened engagement with Beijing and other countries.
In early August, an Indonesian navy frigate made a port call in Japan and held a joint exercise with the MSDF. Less than two weeks later, the vessel participated in a joint exercise with the Chinese navy east of Taiwan.
It was the first time China had conducted such exercises in the area with another country and it drew strong protests from Taiwan.
Mokhamad Luthfi, a lecturer at Al-Azhar University Indonesia, said the Indonesian navy appeared "insufficiently aware of the sensitivity" surrounding cross-strait issues.
At the same time, he said the administration of President Prabowo Subianto is unlikely to pick sides between Japan and China, as both countries remain indispensable economic and investment partners for Indonesia's development.
Hirohito Ogi, a senior research fellow at the Institute of Geoeconomics, pointed out that unlike the Philippines, which shares many of Japan's security concerns, Indonesia's primary objective is to strengthen its domestic defense industries.
Indonesia has pursued defense cooperation with a wide range of countries under Prabowo's military modernization policy. Such an approach reflects Jakarta's longstanding preference for maintaining strategic flexibility rather than aligning itself closely with any single partner.
Indonesia's participation in South Korea's KF-21 fighter jet development program also underscored the importance of evaluating a partner country's track record before embarking on major defense projects, Ogi said.
After Jakarta struggled to meet its original financial obligations, South Korea and Indonesia revised their cost-sharing arrangement in 2025. Ogi said the case illustrates why Japan should carefully assess to what extent a partner will fulfill agreements when pursuing large-scale defense cooperation initiatives.
"It will become increasingly important for Japan to assess how far the other country is willing and able to cooperate, given Japan's limited financial and human resources," he said.
Regarding how MSDF destroyers would be transferred to partner countries, a Japanese Defense Ministry official said no specific decision has been made, including whether they would be sold or provided free of charge.
