Australia would have to heavily rely on America to crew nuclear submarines "for a long time" if it buys US Virginia class vessels, a defence expert says.
Media reports suggest up to five of the American submarines will form the initial part of a landmark defence agreement between Australia, the UK and US under the AUKUS partnership.
The deal involves Australia buying three Virginia class submarines in the early 2030s with the option to buy two more, Reuters reported.
A forward deployment of US submarines in Western Australia by 2027 has also been flagged.
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, Bloomberg is reported.
While not confirming the deal, Prime Minister Anthony Albanese said he will announce the details in San Diego on Monday (US time) alongside US President Joe Biden and UK Prime Minister Rishi Sunak.
He will then hold bilateral meetings with both.
"We're great friends. We have over a century of standing side by side during peacetime and during conflict," Mr Albanese told reporters on Thursday during a visit to India.
Australian National University's 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.
Having a high proportion of the crew being American would force Australia to rely on the US for a long period of time, he added.
"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 said.
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."
Defence Minister Richard Marles said nuclear submarines would be a massive industrial endeavour with the military never having operated "capability at this level".
"This will contribute to the technological advancement of our wider economy," he told parliament.
"As Australia invests in its defence, as we acquire this nuclear-powered submarine capability, we do so as part of making our contribution to the peace and the stability of our region."
South Australian Premier Peter Malinauskas said he wanted submarine construction to start in Adelaide 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.
"But we want to see it happen ASAP."
Opposition foreign affairs spokesman Simon Birmingham said it was 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 it was also important the government cut any red tape preventing the smooth transfer of technology and skills between the three nations.
Opposition Leader Peter Dutton said the coalition would support the government's pathway and "fight to make sure the outcome is achieved as quickly as possible".
with Reuters
