Japan is considering sending advanced F-35s and other fighter aircraft on rotational deployments to Australia and expanding the scope and complexity of joint exercises, as the two seek to deepen not only bilateral ties, but also trilateral security ties with the United States.

During “two-plus-two” talks held Friday evening in Tokyo, the nations’ foreign and defense ministers agreed to step up both military cooperation and exchanges, announcing that Tokyo is considering welcoming Australian Air Force F-35s in Japan next year for the first time to participate in Exercise Bushido Guardian.

Building on the Reciprocal Access Agreement signed earlier this year, the special strategic partners are also considering options to conduct bilateral submarine search-and-rescue training as well as amphibious operations and guided weapon live-fire drills as part of efforts to increase interoperability and advance the scope and forms of the defense cooperation.

They also plan to expand air-to-air refueling pairings between the Air Self-Defense Force and the Australian Air Force.

The two sides also agreed to enhance cooperation on strategic capabilities, including long-range guided weapons, integrated air and missile defense and undersea warfare while bolstering trilateral cooperation with the United States. The latter includes increasing training opportunities with the U.S. forces in northern Australia, enhancing intelligence, surveillance and reconnaissance cooperation, and engaging in trilateral exercises.

In terms of defense technology cooperation, Japan and Australia agreed to elevate equipment, science and technology and industry cooperation in various ways, including by finalizing a research, development, test and evaluation arrangement and enhancing collaboration in autonomous systems across all domains.

The talks in Tokyo followed a two-plus-two meeting between the United States and Australia on Tuesday, which saw the two countries invite Japan to increase its participation in defense initiatives in Australia, including troop rotations, to set up a united front amid China’s growing military capabilities.

“Essentially what is happening is the establishment of a deeper defense cooperation agreement between the U.S., Japan and Australia that now extends to force posture — that is, where the Self-Defense Forces are deployed,” said Malcolm Davis, a military expert at the Australian Strategic Policy Institute (ASPI).

This would suggest that SDF personnel and assets could deploy to and from Australia on a more regular basis for multinational exercises, but also for extended rotational deployments and during operations.

Thomas Wilkins, a Japan security expert at ASPI, said such cooperation would facilitate Japan's integration with Australian and U.S. forces, making the SDF more capable and competent when working with allies and partners, while also opening up the prospect of coalition operations in the event of a regional conflict.

“A more capable and integrated trilateral front may contribute toward deterring regional powers contemplating acts of aggression,” he said.

At the same time, he added, this would facilitate the practical development of the SDF to protect the Australian Defence Force’s assets.

Yet, this must be put into practice and requires training, Wilkins noted.

The move would also imply establishing and enhancing base infrastructure in Australia that is better suited to supporting U.S. and Japanese forces, and in particular during wartime.

In fact, such efforts appear to be already under way, as Washington announced Tuesday that it will increase the rotational presence of U.S. air, land and sea forces in Australia, including rotations of bomber task forces and fighters. The announcement follows reports that Washington is funding a project to build an aircraft parking apron by 2026 capable of accommodating up to six B-52s and other aircraft at the Tindal air base in northern Australia.

The Pentagon also said Tuesday that it will pre-position stores, munitions and fuel in support of U.S. capabilities in the area, co-develop logistics at certain airfields, and expand locations for U.S. Army and U.S. Marine Corps forces in order to enable exercises, activities and further opportunities for regional engagement.

This bolstered U.S. presence in the Northern Territories will create scope for more and new forms of trilateral activities with Japan.

“These training areas are extensive and have significant infrastructure for joint exercises not available elsewhere,” Wilkins said.

They are ideally suited to “multidomain” — land, air, sea, cyber and space — operations, which Japan is specifically seeking to develop as part of its “multidomain defense force,” he added.

Meanwhile, such cooperation would signal to Beijing that there is growing determination and resolve by these countries to stand firm in the face of Chinese provocations and threats, Malcom noted.

“It would make it clear that in a crisis — if Beijing uses force against Taiwan, or in another context — China would likely be entering a war against all parties.”

Friday’s announcement is just the latest in a series of measures that have brought Tokyo and Canberra closer together.

In January, the two sides signed a defense pact that will allow their militaries to train on each other’s territories. Once ratified by legislators in both countries, the Reciprocal Access Agreement will be Japan’s first accord covering a foreign military presence on its territory since the 1960 Status of Forces Agreement with the U.S.

Another key step was the signing in late October of a new joint security declaration that creates a consultation mechanism between the “semiallies” for responding to “contingencies” — a term often used to describe a conflict over Taiwan. The move marked the first such mechanism involving Japan outside of its alliance with the United States.

“The big frame is this: Australia has become Japan’s second-most important security partner after the U.S.,” said Brad Glosserman, deputy director of the Center for Rule-Making Strategies at Tama University, noting that the two countries are working ever more closely together in pursuit of regional security and stability.

Meanwhile, experts have also raised the possibility of the U.S., U.K. and Australia working together with Japan on developing critical and emerging technologies, as there is considerable overlap between the needs of the parties. In particular, they all seek advanced autonomous systems as well as undersea warfare, cyber, space, hypersonic and counter-hypersonic capabilities.

“Although we are unlikely to see Japan officially join the AUKUS security pact, Tokyo will likely seek to participate in some of the working groups looking at areas of high technology and defense systems, from which all parties can benefit from Japan's involvement,” Wilkins noted.