By Hirohito Ogi
In April 2024, the Australia–UK–US trilateral security cooperation framework (AUKUS) declared their intention to consider ‘cooperation with Japan on AUKUS Pillar II advanced capability projects’. AUKUS currently involves developing nuclear-powered submarines (Pillar I) and advanced defense technologies (Pillar II). The following Japan–US summit statement reiterated this intention, with the addition of the recognition of ‘Japan’s strengths’.
While the media reported that the United Kingdom and Australia hesitated to extend AUKUS membership to Japan due to their ‘concerns’ about Japan’s information security system, the three parties still chose to pursue cooperation with Japan. Though it is unclear which part of Japan’s information security system concerns the two countries, they still recognise the value of its potential contributions.
Japan’s inclusion in AUKUS will undoubtedly strengthen the perception of the Japan–US alliance as the central axis of the alliance network in the Indo-Pacific. But Japan’s cooperation with or within AUKUS is less critical, given that AUKUS primarily serves as a framework for advancing defense technologies, rather than an alliance committed to defense during contingencies.
Ultimately, Japan can cooperate in developing advanced capabilities with the United States, Australia and the United Kingdom without participating in AUKUS. Plans are already underway to develop Glide Phase Intercepters and jet trainers with the United States, as well as Global Combat Air Program fighter jets with the United Kingdom and Italy. Japan also has plans to develop undersea communication technology with Australia and unmanned collaborative combat aircraft with the United States and Australia.
Because all of these examples already entail advanced defense technologies within the scope of AUKUS Pillar II, Japan does not have to be an AUKUS member, unlike Australia, which requires AUKUS to acquire nuclear-powered submarines. Increasing the number of participants in joint development programs does not necessarily mean an increase in their effectiveness. Instead, it could exploit the maximum utility by choosing optimum combinations of partners depending on the nature of individual projects.
Still, there are several reasons why leaders of the AUKUS countries will be better off considering the possibility of Japan as a fourth member. The alignment of their views on the deteriorating security environment and the defence capabilities required to address these challenges are also consistent. Deterrence by denial, through acquiring ‘asymmetrical advantages’ against a peer competitor, namely China, would be one of them.
A prime example of this would be enhancing uncrewed undersea capabilities, which would enable them to acquire the means to degrade Chinese maritime forces. Discussing and collaborating on future capabilities among states with similar security requirements could stimulate creative ideas to materialise key technologies necessary for those capabilities.
Collaboration through AUKUS will also enhance capability integration and standardisation among partners. While it is possible to develop elemental technologies independently, seamless integration into specified systems — particularly with the prospect of combined future production or interoperability — demands early stage and coordinated partnership efforts. Given the unique constraints of the undersea environment, where radio frequency transmissions would be difficult, establishing reliable underwater communication in a standardised and integrated manner would be critical. Specifically, it will be necessary for command, control and communication between crewed and uncrewed platforms, and for connecting with platforms of friendly forces.
To this end, Japan has been heavily investing in research and development of undersea wireless communication technologies. This resulted in the start of the joint research project between Japan and Australia on undersea wireless acoustic communication for uncrewed platforms, announced in January 2024. Given that connectedness will be critical for the operational deployment of swarming undersea drones in the future, cooperating with Japan on these strengths will not only enhance Pillar II technologies but, also help in standardising capabilities among allies and partners.
AUKUS could accelerate technological exchanges with Japan by rationalising export control and information security regulations, as is the case among the three countries. Japan’s regulations — especially its arms export control regulations — are unique, if not peculiar, and may require a lot of effort to verify and ensure compatibility with the other three countries’. But if successful, such efforts will create opportunities for Japan to explore international markets and for the other countries to increase collaboration with Japan in individual programs.
Ultimately, it is understandable that the four countries want to be careful about rushing into the ‘JAUKUS’ framework, given that such an arrangement is not imperative. But if they all see constraints in their individual joint projects as noted above with a case-by-case approach, it may be a sign to resume this discussion. In the meantime, the parties should not stop individual efforts to invest in advanced defence technologies and also not close the door on the potential for collaboration.
