PERTH >> In the control room of the American Virginia class attack submarine USS Minnesota, off the Western Australian coast, sonar operators adjust to the chatter of dolphins in new waters where the U.S. submarine presence will soon grow significantly.

On a training exercise from its home port in Guam, USS Minnesota is a forerunner to four Virginia class submarines that will be hosted at a Western Australian naval base from 2027, under the AUKUS partnership to transfer nuclear submarine capability to Australia.

Crew use video game joysticks to interrogate screen images from a photonic mast that has replaced a periscope. Life aboard can mean up to 100 days without seeing sunlight, and intermittent communication with families via email to maintain stealth.

Commanding officer Jeffrey Corneille says the Virginia class submarine is “the most advanced warship in the world”.

“If someone wakes up and they say ‘Is today the day?’, we make sure that they say ‘Maybe not’,” he says, describing its deterrent role.

Around 50-80 United States navy personnel will arrive by the middle of the year at Western Australia’s HMAS Stirling base, which is undergoing an A$8 billion ($5 billion) upgrade to prepare for the “Submarine Rotational Force West”, Australian officials have said.

In two years, those numbers will swell to hundreds of U.S. navy personnel and support crew.

The location of HMAS Stirling, closer to Asia and the Indian Ocean than the U.S. Pacific fleet headquarters in Hawaii, is strategically important to the United States, said Peter Dean, director of Foreign Policy and Defence at the United States Studies Centre at the University of Sydney.

“Defending the Indian Ocean against rising Chinese capabilities and power is important,” he said.

The Virginia submarine program has been exempted from Pentagon budget cuts as the Trump administration focuses less on the Middle East and Europe, and more on the Indo Pacific, he said.

The Trump administration’s number three Pentagon official, Elbridge Colby, told a U.S. Senate confirmation hearing this month the attack submarines are “absolutely essential” for making the defence of Taiwan viable, and production rates must be lifted to first meet U.S. needs and also to fulfill its obligations to sell submarines to Australia under the AUKUS pact.

The USS Minnesota moved its home port from Hawaii to the U.S. Pacific territory of Guam, closer to Taiwan and the only forward-deployed U.S. submarine base, in November.

A Chinese navy task group that circumnavigated Australia in February and March, holding unprecedented live fire drills off the east coast that disrupted commercial airlines, before passing Western Australia to coincide with the USS Minnesota’s port call and heading into the Indian Ocean, has highlighted China’s ambition to operate more frequently in Australia’s neighbourhood, Australian officials said.

Under AUKUS, Australia’s most expensive defence project, Australia will buy two used Virginia class submarines next decade, and build a new class of nuclear powered submarine with Britain, to replace its ageing diesel powered fleet.

In preparation, there are 115 Australians in the U.S. nuclear navy training pipeline or on Virginia submarines, plus 130 training for nuclear submarine maintenance at Pearl Harbor in Hawaii, U.S. navy officials said.