As China’s regional influence continues to expand, Japan faces the challenge of balancing strategic priorities within the Association of Southeast Asian Nations (Asean). Amid concerns over weakening regional unity and the United States’ declining engagement, Tokyo seeks to strengthen partnerships with key nations while maintaining relations with all member states.
Masafumi Ishii, director of the Resona Research Institute, a think tank and consulting firm, and former Japanese ambassador to Indonesia, discusses Japan’s evolving geopolitical approach, resource limitations, and the critical role of human capital in sustaining Southeast Asia’s stability and prosperity.
What is your main concern about Asean today?
My foremost concern is the weakening unity within Asean. There is no clear leadership to strengthen cohesion. Without unity, Asean loses both its strength and influence.
Internal disputes — such as border tensions between Thailand and Cambodia, and the Myanmar crisis — continue to undermine regional solidarity. I believe Indonesia, as the largest and historically most influential member, should take the initiative to rebuild Asean’s collective leadership.
How is the United States’ behaviour affecting the region’s stability?
The United States appears to be losing interest in maintaining peace and prosperity in Southeast Asia. Instead of supporting free trade, it imposes reciprocal tariffs — a poor way to make friends.
What worries me more is that Washington seems to be dismantling the very rules-based order it built after World War II. Without that order, there can be no lasting peace or stable growth.
We will make every effort to maintain the United States’ interest in the region because we need to keep the United States’ attention. But at the same time, we need to face the reality, which is some kind of vacuum created by the withdrawal of the United States.
With the US stepping back, who could fill the resulting power vacuum?
While the US is not gone, its disengagement demands a response. I personally hope Japan can play a more active role. Southeast Asian nations see Japan as a consistent and reliable partner, with fewer political complications.
If Japan chooses to engage more deeply, it will be welcomed by the countries in the region. I hope the new Takaichi administration, which I think has a strategic perspective, will start doing something to engage Southeast Asia.
How will Japan adjust its regional strategy under these changing conditions?
Japan is revising its strategic document to reflect new realities. Our Official Development Assistance (ODA) is limited, and Japan is no longer as wealthy as before.
The updated strategy will provide clear guidance for prioritisation — determining which countries and sectors deserve the most attention to maximise our regional impact.
How does Japan prioritise its Asean partners?
The Japanese foreign ministry has been conducting opinion surveys in other countries every two years since 2008. We’ve been asking questions including which country do you think will become more important for your own country, or which country do you think you are going to rely on more in the future?
Of course, some countries’ results say China, some countries say Japan, some countries say possibly the United States. The result shows that Asean countries are divided into four groups even though you haven’t made it public.
In public, you say that you never choose between China and the United States. That’s understandable. Without making a choice, you have to do good things, maintain good relations with everybody so that you can get the best out of everybody, considering the positioning of your countries. That is the way that should be.
The first group always chose Japan. Japan will become more important than any other countries. The countries (in this group) are Indonesia, Vietnam, and the Philippines.
The second group is the countries where the result swings between China and Japan according to the administration. These countries are Thailand, Malaysia, and Myanmar.
The third group, Cambodia, Laos, and Brunei, lean towards China, while group four is the exception, which is obviously always Singapore. The country publicly favours China but cooperates militarily with the US.
With limited resources, Japan will focus its time and energy on Group 1, while maintaining balanced engagement with all.
Why are Indonesia, Vietnam, and the Philippines considered Japan’s core partners?
These nations are confident and independent enough to resist pressure from China. They value Japan’s support as they maintain sovereignty and stability.
Like Japan, they prefer cooperation without domination. With populations exceeding 100 million, they are the engines of Asean’s future growth and share Japan’s interest in maintaining an open, rules-based order.
This is reflected in (former) prime minister (Shigeru) Ishiba’s recent travel schedule, which focused his limited time on visiting the Group 1 countries, notably Indonesia, Vietnam, and the Philippines.
What are the key sectors for future Japanese engagement in these priority nations?
Key areas include infrastructure, artificial intelligence, technology, and human resource development.
Japan supports regional connectivity through cross-border infrastructure projects such as the East-West and North-South corridors. Investment in vocational training is also crucial to improving productivity and creating a mutually beneficial exchange of talent.
How is Japan preparing to address its own domestic demographic crisis?
Immigration is becoming unavoidable for Japan. An ageing population and labour shortages mean we need both skilled and unskilled workers from abroad.
Politically, it remains sensitive, but economic survival depends on it. We must open our labour market gradually and manage the process through strong leadership and public understanding.
This will require Japan to start a public discussion and adopt a comprehensive immigration policy guided by strong political leadership.
How does Japan manage relations with China while deepening Asean ties?
Our approach must be carefully calibrated — small enough not to provoke China but significant enough to reassure our partners.
Japan must avoid any perception that it seeks to divide Asean.
The goal is to strengthen collective resilience, not to compete for allegiance.
Under Prime Minister Takahashi’s leadership, what direction do you expect Japan to take?
Prime Minister Sanae Takaichi is instinctively tough on China. While she understands Asean’s need for engagement with Beijing, she will likely adopt a more strategic stance.
On immigration, her government may eventually moderate its position as economic realities and labour demands intensify.
Ultimately, Japan must act decisively — not only to safeguard its interests but also to help preserve stability in Southeast Asia under China’s growing shadow.