Can Japan provide stability to Southeast Asia amid US uncertainty?

Japanese Prime Minister Shigeru Ishiba’s to Malaysia and Indonesia signify the country’s desire to be a stable force in Southeast Asia with deeper military, economic and green energy ties as Trump takes office and China’s influence continues to grow.

Petronss refinery2
Malaysia's national oil company Petronas will be collaborating with Japanese companies to develop hydrogen energy technologies, following Japanese Prime Minister Shigeru Ishiba's visit to Malaysia in January. Image: Bryan Yong

Japanese Prime Minister Shigeru Ishiba’s visit to Malaysia and Indonesia from 9 to 12 January 2025 marked his first bilateral overseas trip since taking office. It reflects Japan’s intent to strengthen ties with Asean countries amid shifting global dynamics.

With China’s growing influence in the region and the return of US President Donald Trump creating uncertainties, Ishiba’s engagements underscored Japan’s desire to diversify its foreign diplomacy strategy. This helps to ensure Japan’s stable role in the Indo-Pacific while serving as a vital link between Asean countries and its formal ally, the US.

The decision to visit Malaysia and Indonesia is not surprising. Both countries are key members of Asean. Malaysia, as Asean chair this year, is an influential voice in the region, while Indonesia is the bloc’s largest economy, most populous nation and a member of the G20 and BRICS.

During his visit, Ishiba announced significant investment commitments, including US$815 million for projects in Indonesia. These initiatives focus on critical areas such as port expansion, human resource development for government officials, and green energy. In Malaysia, discussions centred on advancing trade, including semiconductors, strengthening energy security and carbon capture, as well as strengthening the regional supply chain.

Ishiba’s visit also advanced Japan’s security partnerships in Southeast Asia. Apart from Japan’s Official Security Assistance to provide surveillance and patrol equipment such as high-speed patrol boats to like-minded countries like Malaysia and Indonesia, a key highlight was discussions with Indonesia on plans to co-develop a warship for the Indonesian Navy. This highlights the growing depth of their defence ties.

Japan’s overtures to Malaysia and Indonesia — and other Southeast Asian countries such as the Philippines and Vietnam — underline how the formal US ally is playing a key role in linking these countries to a growing coalition led by Tokyo and Washington.

In August 2023, Japan, South Korea and the US formed a new trilateral partnership, enabling them to adopt common positions on regional security. In April 2024, the US and Japan incorporated the Philippines into a historic trilateral arrangement to bolster the “free and open international order based on the rule of law”. The group held a virtual meeting between the leaders of the three countries on 12 January 2025 to solidify their collective security posture in the Indo-Pacific.

As a key US ally and a critical frontline state in the South China Sea disputes, the Philippines plays a pivotal role in Japan’s regional security strategy. Over the years, Japan has been instrumental in enhancing the Philippines’ maritime capabilities through targeted initiatives, including bolstering maritime domain awareness, conducting capacity-building programmes, and supplying patrol vessels.

Ishiba has touted his vision of an “Asian NATO” — a formal alliance of US allies in the region arrayed against a shared threat (read: China). This is unlikely to materialise, given that many Southeast Asian countries have more sanguine perceptions about China’s rise and are wary of latching themselves to any formal military alliance. But Ishiba will get more traction in expanding a network of like-minded security partners to uphold what is termed the “rules-based order”, based on shared principles such as freedom of navigation and adherence to international law.

A good example would be Super Garuda Shield 2024, an Indonesia-US military exercise carried out in East Java, which saw the participation of Japan, Brunei, Thailand, and Singapore, among other extra-regional countries. Japan has also increased the number and scale of military exercises in the Indo-Pacific, including the Talisman exercises involving the US, Japan, Australia, South Korea, and observers from the Philippines, Singapore and Thailand.

Furthermore, QUAD-lite arrangements, which involve Quad members as well as those between Quad countries and regional countries, continue to proliferate. They involve Japan in configurations such as the US-Japan-Philippines, Australia-India-Japan and US-Japan-Australia trilaterals. This enables Japan and its partners to pursue their national interest in bolstering regional security.

However, Japan’s endeavours to expand its security footprint in Southeast Asia face significant challenges. Domestically, constraints such as limited defence budgets and political sensitivities surrounding Japan’s pacifist Constitution hinder the government’s ability to sustain large-scale security commitments.

Trump’s insistence on allies increasing their defence contributions could pressure Japan to shoulder a greater share of regional security responsibilities. In his first term, Trump reportedly called on Tokyo to more than triple its host-nation support for US troops to US$8 billion.

Japan also has growing concerns nearer to its home islands. According to a study by Nikkei Asia, Sino-Russian naval activities around Japan’s southwestern islands rose from 50 in 2023 to 80 in 2024. Tokyo is also concerned about Russia’s growing security ties with North Korea.

Despite these challenges, Ishiba’s Southeast Asian visits demonstrate Japan’s recognition of Southeast Asia as a linchpin in its Indo-Pacific strategy. At the same time, Japan has been consistent in strengthening ties with the US.

It was one of the first allies to meet the new US administration, as exemplified by the meeting between Foreign Minister Takeshi Iwaya and Secretary of State Marco Rubio, and Rubio’s meeting with the QUAD (US, Japan, Australia, and India) foreign ministers just a day after Trump’s inauguration. As Southeast Asia’s most trusted partner (as reflected in the State of Southeast Asia surveys), Japan is in a good position to serve as an important bridge between Asean and the US.

Joanne Lin is a Senior Fellow and Co-coordinator of the Asean Studies Centre at ISEAS – Yusof Ishak Institute.

William Choong is a Senior Fellow at the ISEAS – Yusof Ishak Institute and Managing Editor at Fulcrum.

This article was first published in Fulcrum, ISEAS – Yusof Ishak Institute’s blogsite.

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