In a year that saw a significant deepening of Japan–Australia relations, a watershed moment of 2022 was the revision of the Japan–Australia Joint Declaration on Security Cooperation, first signed in 2007. The revised document lays the groundwork for significantly closer bilateral cooperation in defence and security.

The joint statement accompanying the declaration said the Japan Self-Defense Forces would train and exercise in northern Australia to increase interoperability with the Australian Defence Force. This has generated expectations that, in conjunction with the implementation of the Japan–Australia reciprocal access agreement, further high-level cooperation will take place in both nations. The Northern Territory, as the main staging area for cooperation between the two militaries in Australia, offers a range of opportunities and resources and a solid foundation for mutual defence cooperation.

So, with the joint declaration as guidance, how will defence officials in Japan and Australia take advantage of the territory’s special characteristics to plan capability improvements?

Japan’s ground forces participate in the Australian Army Skill-at-Arms Meet and Exercise Southern Jackaroo along with the US Marine Corps. Since 2015, Japan has joined in Australia’s Exercise Talisman Sabre, which has improved trust and tactical skills in the units involved.

For Japan, a major advantage of exercising in Australia is the abundant training area available. During Southern Jackaroo in 2019, Japanese 155-millimetre howitzers were able to engage targets 25 kilometres away. At Talisman Sabre that year, the Japan Maritime Self-Defense Force conducted long-range manoeuvres and joint amphibious operations. Talisman Sabre in 2021 reflected the importance of joint training for amphibious units from the US, Japan and Australia.

The Northern Territory has detailed the core capability improvements to be made at air and maritime bases by the territory and federal governments. Four of the bases have been refurbished as part of the US force posture initiatives.

ASPI’s John Coyne and Malcolm Davis have written much about the advantages and opportunities that northern Australian presents. NT security expert Alan Dupont has strongly advocated for a build-up in defence capability and infrastructure upgrades in the north.

The 2022 joint declaration covers the mutual use of facilities including maintenance. Japan can more proactively engage in its own defence by collaborating with the ADF and by increasing its infrastructure investment in northern Australia.

At the December 2022 AUSMIN talks, Australia and the US agreed to expand locations for the US Army and US Marine Corps to enable exercises, activities and further opportunities for regional engagement. The decision to expand opportunities for Japan to participate in US and Australian defence activities and force posture initiatives in Australia was significant.

Japan’s national security strategy, released in December 2022, emphasises the need to build and expand networks between allies and partners and to explore ways to strengthen deterrence. The national defence strategy released concurrently with the security strategy says cooperation with Australia should include exercises and rotational deployments, and that Japan would consult and collaborate with Australia on logistics support and information sharing.

While the Japan Self-Defense Forces will continue to take part in exercises in Australia, rotational deployments in the nation’s north will provide many opportunities to build relations with the region.

Grant Newsham, a research fellow at the Japan Forum for Strategic Studies, has suggested that six-month deployments of amphibious units from Japan’s ground forces and their joint training with amphibious elements of the Australian Army in northern Australia would provide a great opportunity to create an entirely new force. Moreover, if Japanese units were dispatched for the long term to northern Australia, it would become much easier for them to engage in capacity building with the ADF in Timor-Leste and Pacific island nations.

To what extent the defence agencies of Japan and Australia can realise the ambitions laid out in their security cooperation statement remains to be seen. The geographic advantages of northern Australia and the benefits to be accrued from exercises and support for capability building are more important than ever. They will make defence cooperation between Japan and Australia more meaningful and will contribute to the ultimate goal of regional peace and stability.