The fast-attack submarine USS Vermont arrives for scheduled maintenance at HMAS Stirling in Western Australia, on Oct. 29, 2025. (Jaxsen Shinners/Australia Department of Defence)

A U.S. Navy fast-attack submarine is undergoing maintenance at an Australian base where a multinational force of nuclear-powered boats may be in position in just over a year, according to the Australian Defence Department.

The Virginia-class USS Vermont docked Oct. 29 at HMAS Stirling, Western Australia, marking a significant advance toward the country’s goal of operating and maintaining nuclear-powered submarines, according to a department news release that day.

Australia is responsible for significant maintenance on the Vermont, according to the Defence Department.

The work required on the Vermont will be more complex than what Stirling provided the USS Hawaii last year and reflects the type of work needed to support the submarine rotational force, the release states. The Pearl Harbor Naval Shipyard in Hawaii is collaborating on a maintenance period in Australia for the first time, according to the release.

The work will provide valuable training and test infrastructure and systems at Stirling, Vice Adm. Jonathan Mead, director general of the Australian Submarine Agency, said in the release.

Australia is developing the capability to service the boats under the AUKUS defense pact, a defense partnership between Australia, the United Kingdom and the United States.

The commander the U.S. Pacific Fleet Submarine Force, Rear Adm. Chris Cavanaugh, speaks to the press at HMAS Stirling, Western Australia, on Oct. 29, 2025. (Zac Dingle/Australia Department of Defence)

The Pentagon is reviewing the 2021 agreement, which aims to establish Submarine Rotational Force-West at Stirling, with one British and four U.S. submarines stationed there on a temporary basis from as early as 2027.

The review is underway amid concerns about whether U.S. industry can supply Australia with submarines beginning in the early 2030s while meeting Navy needs.

Nevertheless, the primary upgrades at HMAS Stirling, valued at $5.2 billion, began in August with reports that 3,000 to 9,000 Americans could arrive with the submarines.

Ahead of the international force’s deployment the U.S. has been sending Virginia-class boats to Stirling and training Australian technicians to maintain them.

In August 2024, the fast-attack submarine USS Hawaii and submarine tender USS Emory S. Land spent several weeks at the base, where U.S. and Australian crew members aboard the tender performed maintenance on the submarine.

In February another Virginia-class vessel, the Guam-based USS Minnesota, also called at Stirling.

The submarine’s crew of 134 includes 13 Australian sailors, the release states. Virginia-class subs are built to accommodate special operations and also carry conventional torpedoes and Tomahawk cruise missiles, according to a Navy factsheet.

“Australia is firmly on track to commence Submarine Rotational Force – West in 2027 which will further accelerate Australia becoming sovereign ready to safely own, operate and maintain our first sovereign Virginia-class submarine from the early 2030s,” Mead said.