In a bid to deter Chinese aggression in the Indo-Pacific, Canberra will acquire three US Virginia-class nuclear submarines as a stop-gap from approximately 2033 before a new SSN AUKUS-class hybrid vessel arrives in Australian waters a decade later.

The cost to taxpayers of the trilateral deal with the US and UK will come in at an eye-watering $268-$368 billion over the coming three decades.

The plan will take $9 billion from the budget's bottom line across the next four years and $50-58 billion within a decade.

The annual cost will then be around 0.15 per cent of GDP until the mid-2050s, but there are warnings about the accuracy of the forecasts due to the unpredictability of inflation in three decades' time.

An American submarine for Australia will roll off the production line every three years before the new AUKUS class will be built at a similar rate from 2042. The sale will need approval from Congress.

Australia's current Collins-class submarines are due to come out of service in the late 2030s.

The plan ensures Australia will always have a baseline fleet of six submarines and have the option to buy an additional two Virginia-class submarines should there be any delays.

The nuclear-powered submarines can stay at sea for as long as the crew have food, extending Australia's capability from the weeks the Collins class can remain underwater.

The UK will construct and use the first AUKUS submarine from the late 2030s and acquire an estimated eight to 12 of the same type.

The British design was favoured over the American one, with the Virginia class set to stop production in the mid-2040s and Australia requiring a continuing solution.

It'll take an estimated 100 to 110 people to crew the new AUKUS class, significantly higher than the 60 it takes to command Australia's Collins submarines.

Four American nuclear-powered submarines and one UK vessel will begin rotating through Western Australian naval bases from as early as 2027 to boost Australia's ability to operate its own vessels in the 2030s and 2040s.

Increased visits from US and UK nuclear submarines will also begin from next year.

Shipbuilders in Adelaide and Western Australia will join those in America and Britain in helping construct the new submarines, with shipyard upgrades to begin this year.

Radioactive waste will be managed in Australia, which has drawn protests from environmental campaigners.

Prime Minister Anthony Albanese said the partnership was about strengthening national security and stability in the region as he announced the plan alongside US President Joe Biden and UK Prime Minister Rishi Sunak in San Diego.

"For more than a century, brave citizens from our three countries have been part of a shared tradition of service in the cause of peace and sacrifice in the name of freedom," he said.

"While we respect and honour the past, through AUKUS, we turn ourselves to face the future."

Mr Biden said the agreement was a testament to the strong ties between the three nations.

"As we stand at the inflection point in history ... the United States can ask for no better partners in the Indo-Pacific, where so much of our shared future will be written," he said.

Australian Associated Press