US President Joe Biden will host Mr Albanese and British PM Rishi Sunakin in San Diego where the government will buy nuclear-powered submarines from the US while launching a mammoth long-term project to build a new fleet in Australia based on a British design.

According to some reports, Port Kembla is firming up as the location of their base.

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Australia is in the market for at least eight nuclear-powered submarines, at a cost of at least $100 billion - the largest defence acquisition in the nation's history.

* Australia will purchase three US Virginia class submarines in the early 2030s, with the option to buy an additional two, Reuters is reporting.

* But Australia may need to invest in the strained American production line in order to secure the US-made vessels, the Wall Street Journal says.

* US nuclear submarines will also reportedly start to rotate through Western Australia from around 2027.

* Australia will then work to build a hybrid nuclear submarine, using a British SSNR design with an American weapons systems and components, according to Bloomberg.

* The American weapons system and upgrades would increase interoperability between the three navies, which would be using common technology.

* The hybrid submarine won't be in the water until the end of the next decade or in the early 2040s.

* Prime Minister Anthony Albanese, US President Joe Biden and British leader Rishi Sunak will unveil the AUKUS submarine deal in San Diego on Tuesday (AEDT).

* The pathway forward is set to be a "genuinely trilateral solution".

* Australian crew will rotate through US and UK nuclear submarines to increase interoperability.

* Australian naval personnel are also studying at US nuclear facilities and colleges to increase their skills.

* The AUKUS agreement will also accelerate the acquisition of guided weapons.

* America's submarine supply chain is already stretched.

* Australia won't be able to crew the larger and more technically complicated Virginia class submarines, increasing reliance on America.

* Similarly, reliance will also be increased because Australia won't have a domestic nuclear industry and have to rely on the US and UK for some repairs.

* Acquiring two different models of nuclear-powered submarines is risky.

* "It is difficult to overstate the step that, as a nation, we are about to take. Clearly, these submarines will have the capability to operate at war, but the true intent of this capability is to provide for the stability and for the peace of our region." - Defence Minister Richard Marles

*"The deterrence is there on full display when you've got these nuclear-powered submarines that can lurk in the waters. Adversaries would think twice about causing harm to our country, knowing that we have this capability." - Opposition Leader Peter Dutton

* "This trilateral co-operation constitutes serious nuclear proliferation risks, exacerbates arms race and hurts peace and stability in the Asia-Pacific. We urge the US, the UK and Australia to abandon the Cold War mentality." - China's foreign ministry spokeswoman Mao Ning

* "These were limitations that had been in place for decades and, just in the past 12 months, the US and the UK have made significant inroads in allowing access." - Navy Vice Admiral Jonathan Mead

* "What matters from South Australia's perspective is building nuclear submarines here ... as soon as possible. We must get on with that task." - South Australian Premier Peter Malinauskas

* "This wasn't about having one of these countries build our boats. This was about all three countries having more boats and so we needed to look at something that would enhance that overall capability." - former prime minister Scott Morrison

Australian Associated Press