The Mogami: Advancing Australia-Japan Defense Cooperation

In August 2025, the Australian government announced its selection of the upgraded Japanese Mogami-class frigate as its new general-purpose frigate. Just one month later, on September 5, 2025, Deputy Prime Minister and Defence Minister Richard Marles met with Japanese Defense Minister Gen Nakatani in Tokyo for the 12th Japan-Australia 2+2 Ministerial Consultations. Later that day, they observed the Japan Maritime Self-Defense Force (JMSDF) frigate JS Mikuma, which is the fourth vessel of the Mogami-class frigate.

This development in shipbuilding cooperation between Australia and Japan will boost Australia’s naval capabilities, enhance interoperability between the two countries, reinforce deterrence against China’s growing influence in the Indo-Pacific, strengthen Australia’s shipbuilding industrial base, and deepen supply chain cooperation between Australia and Japan.

During the consultations, the ministers also recognized that strengthening cooperation with the United States, a key ally for both nations, is critical to realizing their shared objectives. The Australia-Japan naval shipbuilding partnership also presents opportunities to strengthen trilateral cooperation and symbolizes the broader significance of cooperation among U.S. allies to secure peace and stability in the region.

Aligning Security Strategies

Japan’s 2022 National Defense Strategy identified Australia as its closest security partner second only to the United States, under the framework of the “Special Strategic Partnership”. Australia’s 2024 National Defence Strategy stated that the alliance with the United States is fundamental to national security, and that Japan is an indispensable partner for achieving regional peace and prosperity. Both countries view their alliances with the United Sates as a key pillar of their security policies.

Prior to 2014, Japan had effectively prohibited defense exports for decades. However, in response to an increasingly severe security environment, it established the Three Principles on Transfer of Defense Equipment and Technology that year. Despite this policy shift, Japan lost to France in the bid for Australia’s submarine program in 2016 and has made little progress since then, aside from a 2020 agreement to transfer air surveillance radars to the Philippines. The transfer of upgraded Mogami-class frigates to Australia, alongside the recently announced joint development of next-generation fighter aircraft with Italy and the United Kingdom, marks a significant step forward in Japan’s defense export policy and its defense cooperation with allies and partners.

Australia-Japan defense ties date back to the 2003 Memorandum on Defence Exchange. Since then, both countries have steadily cultivated a foundation for joint activities through a series of key agreements, including the 2007 Joint Declaration on Security Cooperation, the 2013 Agreement Concerning Reciprocal Provision of Supplies and Services, the 2013 Agreement on the Security of Information, the 2014 Agreement Concerning the Transfer of Defence Equipment and Technology, and the 2023 Agreement Concerning the Facilitation of Reciprocal Access and Cooperation.

Building on that foundation, both countries are steadily making practical progress through bilateral and multilateral exercises such as Nichi-Gou Trident, Talisman Sabre, and Orient Shield, as well as through the mutual exchange of liaison officers between the Australian Defence Force Headquarters Joint Operations Command and the Japan Self-Defense Forces Joint Operations Command.

Why the Mogami Was Selected

Australia is increasingly concerned about China’s coercive activities in the Indo-Pacific and its expansion of influence and presence in the Pacific Island nations. For example, in November 2023, the Chinese navy used sonar pulses against Australian divers in international waters off Japan, injuring them. In June 2024, Chinese coast guard vessels fired water cannons and blocked an Armed Forces of the Philippines resupply mission in the South China Sea, severely injuring a Philippine sailor. In February 2025, the Chinese navy conducted live-fire exercises in the Tasman Sea without adequate notification, prompting passenger planes to change course mid-flight. In April 2025, China launched large-scale military drills around Taiwan, simulating attacks and maritime blockades.

In response to the intensifying security environment, Australia’s 2023 Defence Strategic Review concluded that the Australian Defence Force’s current force structure is not fit for purpose. It emphasized the need for an enhanced lethality surface combatant fleet and recommended an independent analysis to assess its size, structure, and composition. That analysis, released in February 2024, recommended that the government accelerate the acquisition of 11 general-purpose frigates to replace the aging Anzac-class frigates, with capabilities to secure maritime trade routes, defend the northern approaches, and escort military assets, using a hybrid offshore-then-onshore build strategy. In November 2024, the Australian government announced that the first three ships would be constructed offshore, with the remainder to be built domestically in Australia once production capacity at the Henderson precinct is ready.

The Australian defence minister emphasized that the decision was entirely based on capability. The upgraded Mogami-class frigate selected by Australia offers the following key features:

• Long-Range Navigation Capability: The Mogami provides a range of up to 10,000 nautical miles and a top speed exceeding 30 knots, enabled by its powerful and efficient propulsion system. This supports Royal Australian Navy (RAN) sea lane defense operations, contributing to securing maritime trade routes.
• Missile Strike Capability: The Mogami is equipped with a 32-cell Vertical Launch System, four times as many cells as the eight on the RAN’s current Anzac-class frigate, for surface-to-air missiles such as the Evolved Sea Sparrow Missile, and also carries anti-ship missiles. This can enhance the RAN’s deterrence posture and supports its strategy of denial in the northern approaches.
• Interoperability with U.S. Forces: The Mogami is highly interoperable with U.S. systems. Both Australia and Japan prioritize interoperability with U.S. forces and employ many U.S.-made weapons. This commonality would further strengthen their ability to operate seamlessly alongside U.S. forces.
• Manpower Efficiency: The Mogami offers manpower-saving operations through its Combat Information Center, which consolidates information control functions using advanced automation technologies. Consequently, it can be operated by only 90 crew members, half the approximately 180 required to operate the RAN’s existing Anzac-class frigate. This would significantly ease the RAN’s workforce challenges, which are the most severe among the three services.
• Rapid Construction and On-Time Delivery: Australia’s Hunter-class frigate program has faced cost overruns and delivery delays due to repeated specification changes. In contrast, Mitsubishi Heavy Industries (MHI), the shipbuilder of the Mogami, has a 35-year record of on-time delivery to the JMSDF, thanks to its swift and efficient construction methods and scheduling. To reduce program risk, the Australian version will have minimal changes. As a result, the first Australian Mogami is scheduled for delivery in 2029, with operational deployment targeted for 2030.
   

Strengthening the Shipbuilding Industrial Base

The analysis released by the Australian government also emphasized the need to support Australia’s continuous naval shipbuilding and sustainment industry. The government has stated that it will invest tens of billions of dollars in defense capabilities in Western Australia over the next two decades, creating approximately 10,000 well-paid, high-skilled jobs. However, Australia’s 2024 Defence Industry Development Strategy highlights a shortage of skilled engineers, making workforce development an urgent priority for rapid ship construction.

To address the workforce shortage, the offshore production phase in Japan is essential. MHI could host Australian engineers at its shipyard, providing technical training, such as welding skills, and sharing advanced shipbuilding technologies, including digital engineering. Australian engineers could further develop their skills by working alongside Japanese engineers during ship construction.

A naval ship comprises not only a hull but also numerous onboard systems, including radars, antennas, sonars, sensors, and information processing systems. This means that in addition to MHI, which is the prime shipbuilder for the hull, many Japanese onboard systems companies, such as Mitsubishi Electric, NEC, Hitachi, Fujitsu, and Oki Electric Industry, are involved in the construction of Australian Mogami. For Australian engineers, working with such Japanese industries on system installation would also help them gain and enhance technical skills, facilitating technology transfer to Australia.

During the offshore production phase, Australia could simultaneously advance its own engineer training and infrastructure development at Henderson Shipyard to prepare for the onshore production of the remaining ships. This hybrid offshore-onshore approach would help accelerate the construction of all 11 frigates and the development of Australia’s shipbuilding industrial base.

The Mogami has a projected service life of 40 years. To sustain the long-term operational readiness of the fleet over that period, maintenance and repair capabilities are just as critical as initial construction. Operating common platforms and systems between Australia and Japan could facilitate the shared use and production of spare parts in both countries, thereby supporting long-term sustainability. This would also strengthen supply chain cooperation and aligns with the Pentagon’s Partnership for Indo-Pacific Industrial Resilience initiative, which encourages allies and partners to create a trusted ecosystem of technical cooperation, supply chain resilience, and co-production and co-sustainment collaboration.

U.S.-Australia-Japan Trilateral Collaboration

The U.S. shipbuilding sector faces similar hurdles, including skilled workforce shortages. The construction of the Australian Mogami could offer valuable lessons in engineer training and the adoption of new technologies, supporting efforts to rebuild the U.S. maritime industrial base, as advocated in the executive order Restoring America’s Maritime Dominance.

Importantly, the United States is a key partner in the construction of the Australian Mogami. As noted above, Australia and Japan prioritize interoperability with U.S. forces. Given Australia’s plan to adopt the upgraded Mogami design with minimal specification changes, the Australian version is likewise expected to incorporate many U.S. systems. This presents significant economic opportunities for the U.S. defense industry. Australia and Japan should maintain close coordination with the United States to ensure the timely delivery of these systems.

Enhanced trilateral interoperability will lead to more effective and efficient naval operations among the three countries. For example, it will facilitate the implementation of the new trilateral terms of reference on maritime logistics, signed by the three navies in July 2025. This arrangement includes missile reloading and flexible refueling, enabling faster naval responses in the event of a crisis in the Indo-Pacific.

Conclusion

The security environment in the Indo-Pacific region is deteriorating rapidly as China seeks to shift the regional balance of power in its favor. The challenges posed by Chinese coercion cannot be addressed by any single nation.

The construction of the Australian Mogami through Australia-Japan cooperation stands as a strong example of defense and industrial collaboration among regional partners. It will enhance Australia’s naval capabilities, improve interoperability between the two countries, deliver economic and strategic benefits to Australia, Japan, and the United States, and potentially strengthen trilateral shipbuilding and maintenance bases as well as supply chain resilience in the region.

Moreover, a recent media report stated that New Zealand has also expressed interest in the upgraded Mogami, and the Japanese and New Zealand defense ministers have agreed to maintain close communication regarding a possible frigate deal. Members of the U.S. alliance and partner network should continue to strengthen and expand defense cooperation to reinforce integrated deterrence and ensure a free and open Indo-Pacific.

Moyuru Tanaka is a visiting fellow with the Japan Chair at the Center for Strategic and International Studies in Washington, D.C., from the Acquisition, Technology, and Logistics Agency (ATLA) in Japan’s Ministry of Defense.

The views expressed herein are solely the author’s and do not represent the views of Japan’s Ministry of Defense, nor the government of Japan.