apan and Australia talk of ‘collective deterrence,’ but they don’t seem to have specific objectives. The relationship needs a clearer direction.
The two countries should identify how they complement each other. Each country has two standout areas: Japan has strengths in air and missile defence and in shipbuilding, whereas Australia needs help in both; and Australia has strengths in cybersecurity and its distance from China, both of which offer advantages for Japan.
It’s true that both nations have recently strengthened their special strategic partnership to the point where it has begun to show alliance-like characteristics, such as commitments to consult during regional crises. Yet practical coordination has barely begun. Discussions on bilateral cooperation often end at increasing interoperability—but to what end?
During the Japan-Australia Dialogue and Exchange program, hosted by the United States Studies Centre and the Japan Foundation from July to August last year, I engaged with many Japanese and Australian experts on security issues, including a Taiwan contingency. While many underscored the need for the two countries to deepen defence ties and prepare to fight together should a crisis erupt, there was little clarity on how exactly they should coordinate.
Although some studies are conducted behind closed doors, the overall lack of discussion stems from several factors. Japan has a limited understanding of Australia’s defence capabilities, and the Japanese defence community primarily focuses on implementing established policy. These factors have contributed to stagnation in finding new strategic opportunities.
In Australia, a shortage of Japan-focused security expertise and a preoccupation with the trilateral framework that includes the United States as well as Japan have constrained deeper thinking around bilateral cooperation.
Japanese and Australian foreign and defence ministers said in November that the countries were refining the scope, objectives and forms of their cooperation, a development that will help shape bilateral defence relations. This was in support of what they called strengthening collective deterrence. But all this work is still general rather than specific in nature, and discussion among strategists has been minimal.
Defence cooperation between nations with comparable military power and a reciprocal security relationship typically takes two forms: force aggregation, which enhances overall military capacity through joint operations; and complementary cooperation, which mitigates vulnerabilities by leveraging respective strengths.
Japan and Australia have primarily focused on force aggregation by emphasising interoperability, but this has limitations. China has an overwhelming numerical advantage, with about 1100 fighter aircraft and more than 140 major surface warships. Conversely, Japan has 300 fighters and 52 surface combatants, while Australia has about 100 fighters and plans to expand its fleet from 9 to 26 ships. Given this disparity, simply combining forces would do little to shift the strategic balance without further integration with US forces. Even then, the military challenges would remain immense.
Complementary coordination is needed, too. Both countries face the challenge of China, but their operational priorities differ. While Japan focuses on the East China Sea and the western Pacific, Australia can secure sea lanes of communication in the Indian Ocean and the South Pacific and disrupt adversary lanes. This would help ensure Japan’s access to vital resources and ammunition, sustaining its ability to keep fighting while weakening China’s. Japan’s combat endurance is important for managing the Chinese navy’s threat to Australia.
Functionally, Australia and Japan have distinct strengths, as well as vulnerabilities that the other can help mitigate. Japan faces challenges in cybersecurity and logistical sustainment, while Australia lacks integrated air and missile defence (IAMD) and efficient shipbuilding.
Fortunately, Japan has a strong foundation in IAMD and shipbuilding, while Australia excels in cybersecurity and benefits from a geographically resilient logistical basis. By addressing each other’s weaknesses through increased bilateral exercises, common equipment and systems, and joint defence industry investments, Japan and Australia can build a more resilient defence posture.
Japan-Australia defence complementarity is already taking shape to some degree. Geographic cooperation has been an indirect but longstanding feature for both nations due to US naval strategy since the early Cold War. Functional cooperation has advanced further in recent years. At the Trilateral Defence Ministers’ Meeting in November 2024, Australia, Japan and the US discussed cooperation on IAMD systems. Shipbuilding collaboration will likely begin if Australia chooses a design based on the Japanese New FFM class for its new general-purpose frigates. Cybersecurity cooperation is also advancing through joint exercises between Australia, Japan and the US.
Japan’s ability to sustain a protracted conflict remains a challenge, as its shipyards and ammunition factories are in range of China’s missiles and can be easily targeted. For both nations to make credible contributions to regional deterrence, robust defence-industrial cooperation must be a foundation of effective contingency and operational planning. Beyond shipbuilding, the two countries should look to collaboration on ammunition production to reinforce war endurance capability. They should also consider storing mothballed assets in Australia, such as aircraft that have been retired but are still worth keeping for a while, in case they’re needed.
Deeper ties will need dedicated advocates. Both countries’ strategic communities must define the desired end-state of cooperation and identify opportunities that advance this goal.
