The United States has revealed the first nuclear submarine that will deploy to Australia under the AUKUS agreement, five years after the $386 billion defence pact was signed.
The USS Colorado, a 10-year-old Virginia-class submarine, will make its new home at Western Australia's HMAS Stirling from late 2027, Defence Minister Richard Marles revealed in a joint statement with his US and British counterparts on Tuesday.
It's the first of up to four US submarines, and one from the UK, set to rotate through the base while Australian Defence Force personnel get to grips with owning and operating nuclear submarines.
But Colorado's arrival in Australia will be controversial because of outrage sparked in late May over revelations that the US would deliver lesser equipment than first promised.
The original AUKUS plans were for Australia to receive two used vessels and a new Virginia-class submarine before building one of its own in Adelaide.
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The fact the US would now be sending second-hand vessels was described as "trash" by Tasmanian independent senator and army veteran Jacqui Lambie, but ministers and top military brass at the time insisted used subs were the best option.
Prime Minister Anthony Albanese at the time assured the public AUKUS was going "full-steam ahead" despite tweaks being made to the mega-money deal, which US defence secretary Pete Hegseth reiterated on Tuesday along with Marles and UK defence secretary Wes Streeting.
Colorado is a "fast-attack" submarine, reaching speeds of more than 46km/h, compared with Australia's Collins-class subs' underwater top speed of 37km/h.
While second-hand, the Virginia class is the US' most advanced line of attack submersibles.
The higher-speed, longer-range vessels are needed to help Australia defend its sea trade, Marles has said.
"The selection of USS Colorado ... is a decisive step in strengthening collective deterrence in the Pacific," the joint statement read.
Australia's own nuclear subs will be conventionally armed, but the US has maintained a policy of ambiguity about whether or not assets rotating through the country are carrying nuclear weapons.
Being nuclear-powered means its range is effectively limited only by its crew's need for food and water.
Tuesday's statement says the AUKUS rotation arrangement will abide by all relevant non-proliferation treaties.
