Japan and Australia Deepen Security Cooperation Amid Rising Regional Tensions

Ministers Meet in Tokyo to Bolster Defense

Japanese Defense Minister Shinjiro Koizumi and his Australian counterpart, Richard Marles, convened in Tokyo on Sunday, December 7, 2025, to advance security cooperation between their nations. The meeting, held at the Japanese Defense Ministry, underscored a shared commitment to regional stability amidst escalating concerns over China's activities in the East and South China Seas.

Key Agreements and Defense Acquisitions

A significant outcome of the discussions was the confirmation of progress toward a contract for the Australian Navy to acquire an upgraded version of the Japanese Maritime Self-Defense Force's Mogami-class frigate. This deal is anticipated to be finalized by the end of Japan's current fiscal year, which concludes in March 2026. As part of this initiative, Minister Marles visited Mitsubishi Heavy Industries Ltd.'s Nagasaki shipyard, a manufacturer of the Mogami-class frigates, on Saturday, December 6, 2025.

Addressing China's Actions and Regional Security

The ministers' talks prominently featured discussions on China's 'increasingly coercive actions' in the East and South China Seas. Minister Koizumi specifically addressed a recent incident on Saturday, December 6, 2025, where Chinese military aircraft allegedly locked radar onto Air Self-Defense Force fighter jets. Koizumi stated, 'We will respond firmly and calmly to the incident toward ensuring regional peace and stability,' a sentiment echoed by Marles, who described the situation as 'very worrying.'

Both ministers reiterated their strong opposition to any unilateral attempts to alter the status quo by force or coercion and expressed serious concerns regarding the situations in the East and South China Seas. They also emphasized the critical importance of peace and stability across the Taiwan Strait for regional and international security and prosperity.

Broader Context of Bilateral and Multilateral Engagement

This meeting marked the second direct engagement between Koizumi and Marles, following their previous encounter in Malaysia in November 2025. Their discussions in Tokyo also built upon a broader framework of cooperation, including a quad meeting involving Australia, Japan, the Philippines, and the United States held in Kuala Lumpur on November 1, 2025. During that multilateral gathering, concerns about China's destabilizing actions in the East and South China Seas were also a central theme. The ministers underscored the importance of ongoing defense cooperation and operational coordination in the South China Sea with the Philippines and other like-minded partners, including through regular Maritime Cooperative Activities.