US Secretary of War Pete Hegseth, Australian Deputy Prime Minister and Defence Minister Richard Marles, and UK Secretary of State for Defence Wes Streeting jointly announced the designation of USS Colorado (SSN 788) as the first US Navy Virginia-class fast-attack submarine assigned to Submarine Rotational Force-West (SRF-West), beginning in late 2027, in a joint statement issued by Australia's defence ministry.

Source: Australian Department of Defence — Joint Statement

SRF-West is projected to host up to four US fast-attack submarines and one UK fast-attack submarine on a rotational basis at HMAS Stirling, a Royal Australian Navy base in Western Australia, the statement said. The announcement comes ahead of a US Submarine Maintenance Period beginning later this week, which the partners say will further demonstrate Australia's growing ability to sustain US and UK nuclear-powered fast-attack submarines.

Source: USNI News

An early arrival in Western Australia

Australian Associated Press (AAP) reported on Tuesday that USS Colorado arrived early at HMAS Stirling to allow Australian crews to gain skills maintaining the nuclear-powered vessel, as part of the US Submarine Maintenance Period programme. Six submarines have visited HMAS Stirling under the programme, with Colorado the third to undergo maintenance in the past 12 months, AAP said.

Source: AAP

The joint statement said SRF-West will accelerate Australia's readiness to own, operate, maintain and regulate a sovereign, conventionally armed, nuclear-powered submarine capability, and described the selection as a significant milestone for AUKUS Pillar I and a decisive step in strengthening collective deterrence in the Pacific. It said the rotation will operate under agreements including the US-Australia Force Posture Agreement, and consistently with the Nuclear Non-Proliferation Treaty and, for Australia, the South Pacific Nuclear Free Zone Treaty (Treaty of Rarotonga).

The plan is not without domestic critics in Australia. AAP reported Greens leader David Shoebridge said the presence of US nuclear submarines in Western Australia would put Perth at risk and called for an end to AUKUS — a position the three governments rejected in their statement, saying AUKUS is moving 'full steam ahead', in the words attributed to President Trump and reaffirmed by Prime Minister Albanese and Prime Minister Burnham in the joint text.