As Prabowo arrives in Tokyo, Japan and Indonesia are building faster than they are thinking

Japan has been Indonesia’s largest aid donor for decades. Tokyo has built Jakarta’s MRT system, financed Patimban port and invested $3.1 billion annually in the Indonesian economy. Yet Japan waited nearly two years for Prabowo Subianto’s first state visit after the Indonesian president took office in October 2024.

When a country makes its most patient and long-standing partner wait so long, it is worth asking why.

The answer is leverage. Jakarta withheld the symbolic prize of a state visit while extracting commitments across multiple fronts, and Prabowo arrived in Tokyo this week with promises for frigates, reactor technology and trilateral security arrangements on the table – before flying directly to Seoul to sign a fighter jet deal. The question is not which country Indonesia prefers. It is whether Jakarta has thought through what it is building, simultaneously, everywhere, at speed.

Across three concrete cases, the answer is not yet.

Minerals and reactors: an energy deal with gaps

On March 15, Indonesia and Japan signed a Memorandum of Cooperation covering critical minerals and nuclear energy, on the sidelines of the Indo-Pacific Energy Security Ministerial and Business Forum in Tokyo. The deal has been widely read as an energy story in which Japan secures access to Indonesian nickel and rare earths and Indonesia gets reactor technology it has sought since the 1960s but could never afford to realise.

The transaction looks mutual. But nuclear technology transfer is not a standard trade arrangement. It creates downstream obligations of IAEA safeguards compliance, technology transfer conditions, liability rules, that follow a recipient country regardless of which government is in power. Neither Jakarta nor Tokyo has publicly said how these obligations will be managed, or how they sit alongside Indonesia’s stated goal of energy sovereignty. An MoC signed at a ministerial forum is a statement of intent. The political work that makes it durable at home, in Indonesia, where nuclear power remains contested, has not been done.

Military assistance and the wrong language

Japan’s Official Security Assistance program has expanded rapidly under Prime Minister Takaichi. The OSA budget more than doubled, a 125% increase to ¥18.1 billion for fiscal 2026, with plans to expand to at least twelve recipient countries across Southeast Asia and the Pacific. The proposed trilateral security arrangement with Australia and Japan would include a joint training facility on Morotai, an island whose layered wartime history carries unresolved meaning for Indonesian sovereignty – adding another layer to an architecture neither side has publicly explained.

OSA comes with an explicit framing: recipients are described as “like-minded partners”, countries that have broadly aligned their security posture with Japan and the United States. The Philippines fits that description. Indonesia does not and does not intend to. Jakarta’s bebas aktif doctrine – free and active non-alignment – has been a cornerstone of Indonesian foreign policy since independence. Prabowo has already drawn domestic criticism for decisions perceived to compromise that posture – including joining US President Donald Trump’s Board of Peace – making the question of how far security deepening with Japan can go without triggering a public backlash a genuinely open one. Whether Indonesia becomes an OSA candidate has not yet been asked aloud in the commentary. But the answer requires Tokyo to develop a political language for the Indonesia relationship that it has not yet found. Japan rebuilt Southeast Asian trust over decades through development assistance, infrastructure investment, and cultural exchange. Allowing security commitments to outpace that trust is a risk Japan has managed carefully since the postwar era and should not now treat as a detail.

Seoul, and what the fighter jets reveal

Prabowo will fly from Tokyo to Seoul on 31 March, where South Korea is expected to sign a preliminary agreement to export 16 KF-21 Boramae multirole fighter jets to Indonesia, the first export deal in the program’s history. The timing makes the pattern visible in a way that bilateral coverage of either visit alone cannot.

Set alongside what Indonesia is procuring elsewhere, the picture becomes striking. Indonesia’s current fighter jet pipeline includes 42 Rafale jets from France, up to 36 F-15EX fighters from the United States, 48 KAAN jets from Turkey, and an evaluation of Chinese J-10C fighters, in addition to the KF-21s from South Korea. Each acquisition brings its own maintenance needs, spare parts, training systems, and political relationship. Managing five different suppliers from five different countries, some of whom regard each other with suspicion, is not a strategy that runs itself.

There is a logic to this. Indonesia is using supplier competition as diplomatic leverage, ensuring no single partner gains a hold over Jakarta’s defence capability. That is bebas aktif applied to arms procurement, and it is not irrational. But the KF-21 history is a warning. Indonesia repeatedly delayed scheduled payments and ultimately reduced its financial contribution to roughly one-third of its original commitment, while its renewed diplomatic engagement with Pyongyang raised concerns in Seoul about the possible transfer of sensitive KF-21 technology. Collecting partners is not the same as managing them. A country that cannot sustain its commitments to one supplier while signing deals with four others is accumulating risk faster than it is building capability.

What the summit still needs to say out loud

None of this is an argument against the partnerships Indonesia is building. The case for deeper ties with Japan, South Korea, and the broader East Asian partner network is genuine and well-founded. But Japan has demonstrated it can deliver hardware: frigates, reactor technology, expanding military assistance. Seoul is about to add fighters. What neither relationship has yet produced is political and institutional work – the public explanations, the governance arrangements, the shared language of partnership – that makes the hardware sustainable on both sides over time.

A Jakarta that is seen by its own public as collecting obligations it cannot manage is a less valuable partner to Tokyo and Seoul, not more. Japan in particular, having spent decades rebuilding regional trust, has a direct stake in Indonesia maintaining a credible and coherent non-aligned posture at home. That argument has not been made clearly enough in Tokyo. It should be the starting point for what comes after this week’s summits.