Media reports suggest up to five of the American submarines will form the initial part of a landmark defence agreement between the US, UK and Australia under the AUKUS partnership.
Reuters reported that the deal involves Australia purchasing three Virginia class submarines in the early 2030s with the option to buy two more.
A forward deployment of US submarines in Western Australia by 2027 has also been flagged.
Bloomberg is reporting the new fleet will be based on a modified British design with US upgrades, which would put Australia on the path to acquiring two types of nuclear submarines.
Prime Minister Anthony Albanese says he'll announce the details in San Diego on Monday (US time) alongside US President Joe Biden and UK Prime Minister Rishi Sunak.
He'll then hold bilateral meetings with both.
"This is a joint arrangement between Australia, the United States, and the United Kingdom," he told reporters on Thursday during a visit to India.
"We're great friends. We have over a century of standing side by side during peacetime and during conflict."
Australian National University's Professor John Blaxland says the speculation "flies in the face" of his understanding of Australia's capability.
"I question what is being said because there has been a long recognition that American submarines are very difficult for us to operate because they're a quantum leap in size and crew requirements," he told AAP.
He said having a high proportion of the crew being American would force Australia to rely on the US for a lengthy period of time.
"We will be dependent on American crewing for a long, long time," Prof Blaxland said.
"Is that what we want?"
This is on top of an already strained US manufacturing system.
"I'm sceptical because the American production line is at capacity, so we might not have any capability for years," he added.
The prime minister rejected the suggestion Australia would lose sovereign capability by becoming reliant on the US.
"Australia will retain our absolute sovereignty, 100 per cent," he said.
"That's something that's respected by all of our partners as well."
South Australian Premier Peter Malinauskas said he wanted to see submarine construction in Adelaide begin as soon as possible, with speculation Australia might prop up US production facilities to get its fleet quicker.
"We all accept there is a capability gap that needs to be addressed, particularly given the geopolitical uncertainty that exists in the Asia-Pacific region," he said.
"Nuclear submarines are the most complicated machines that have ever been produced in human history. They're more complex than the space shuttle.
"But we want to see it happen ASAP."
Prime Minister Anthony Albanese is expected to attend an event in San Diego on Tuesday (AEDT) to announce Australia's pathway to getting nuclear-powered subs alongside President Joe Biden and UK Prime Minister Rishi Sunak.
Opposition foreign affairs spokesman Simon Birmingham wouldn't be drawn on the speculation, but said "it's critical Australia achieves the earliest possible access to nuclear-powered submarines".
"As well as the capability to build, sustain and operate them as quickly as possible," he told AAP.
Senator Birmingham said there was a need for all three nations to work together to boost defence and industry capability.
"It's not a commercial procurement, it's a trilateral partnership to produce more and have more submarines to operate in the future," he said.
He said it was also important the government work to cut any red tape preventing the smooth transfer of technology and skills between the three nations.
with Reuters
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