The deteriorating strategic environment in the Indo-Pacific makes an Australia-Japan defence alignment central to maintaining a free and open Indo-Pacific by deterring China in the region.

Australian–Japanese defence alignment will contribute to deterrence by developing interoperability between the two country’s naval forces.

This alignment has become even more important since the December release of the United States’ National Security Strategy, which prioritises deterrence and increased burden sharing among US allies.

On 7 December, Japanese Defense Minister Shinjiro Koizumi and Australian Defence Minister Richard Marles met in Tokyo. They voiced their ‘strong opposition to any unilateral attempts [by China] to change the status quo by force or coercion … in the East China Sea and South China Sea’.

Over the past few years, China has constructed artificial features equipped with missile systems in the Spratly Islands in the South China Sea and made repeated incursions around the Senkaku Islands in the East China Sea. Both Australia and Japan view these actions as a sign of China’s willingness to project power beyond its shores and directly challenge a free and open Indo-Pacific.

Against this backdrop, what Tokyo and Canberra call their special strategic partnership is emerging as a backbone of efforts to deter Chinese adventurism and protect the freedom of navigation that has long underpinned the prosperity of both nations.

Japan has signalled its intent by bringing forward defence spending goals by two years under the new Sanae Takaichi administration. During Koizumi’s inauguration, he highlighted that Japan and the wider Indo-Pacific region face the most severe and complex security environment since World War II. Koizumi has also expressed willingness to abolish a rule restricting the export of defence equipment to five non-combat categories.

There has been an acceleration of convergence in Japan–Australia defence planning and, increasingly, industrial collaboration. In August, Marles said Australia would procure 11 frigates of Japan’s upgraded Mogami class for the Royal Australian Navy. Japan’s Mitsubishi Heavy Industries will build the first three ships in Japan; the others will be built at the Henderson shipyard in Western Australia.

This deal benefits both nations by strengthening defence–industrial capacity and fostering deeper technological exchange, as well as increasing interoperability between their navies.

The A$10 billion frigate deal represents a major leap forward in Japan–Australia defence cooperation. It sends a direct message to Beijing that both nations are committed to defending their vision of a free and open Indo-Pacific as a stable and rules-based regional order.

The frigate deal also signals Tokyo’s willingness to deepen security ties beyond its longstanding alliance with the US, which dovetails with the burden-sharing among allies that Trump administration’s National Security Strategy called for.

Japan is moving away from post-war pacifism to counter the challenges posed by China and other disruptive actors in the region, such as Russia and North Korea.

The upgraded frigates will provide the RAN with a much-needed technological upgrade. They can sail 10,000 nautical miles without refuelling, some 4,000 nautical miles farther  than Australia’s Anzac-class frigates while requiring smaller crews and offering greater firepower ^[1].

This deepening bilateral relationship also bolsters crucial minilateral frameworks. Both countries are active participants in the Quadrilateral Security Dialogue alongside the US and India. In November, the navies of the Quad members participated in Exercise Malabar in the waters near Guam, underlining intensifying cooperation.

Notably, Japan’s increasing engagement with AUKUS lends the partnership vital Asian legitimacy, countering criticism that it is limited in vision as an Anglosphere grouping. Japan has also welcomed renewed US interest in expanding AUKUS to include trusted partners, an indication that Tokyo’s more proactive leadership is reshaping how Washington views the Indo-Pacific balance.

As an example of such cooperation, the US  joined Japan and Australia in Exercise Bushido Guardian 25 from late September to 10 October, resulting in a trilateral air combat exercise held in Misawa, Japan.

Exercises such as these not only project united strength; they also drive collaboration and further military integration, enabling the armed forces of each nation to work together more effectively.

This growing cooperation has raised concerns in China, as expressed by China’s Foreign Ministry spokesperson in Beijing and ambassador in Canberra.

By deepening defence ties with Japan and building a more advanced fleet, Australia stands in a position to seriously contribute to the maritime security and stability of the Indo-Pacific region.

Today, high stakes demand such strong partnerships. Tokyo and Canberra’s special strategic partnership is central to maintaining a free and open Indo-Pacific and offering a credible deterrent to Chinese aggression across the region.