USS Colorado named first US submarine for AUKUS rotations in Australia

The United States, Australia and Britain have named USS Colorado as the first American nuclear-powered attack submarine assigned to Submarine Rotational Force-West, establishing a significant operational milestone for the AUKUS partnership.

The Virginia-class submarine, designated SSN 788, is expected to begin its rotational assignment at HMAS Stirling in Western Australia in late 2027.

The announcement was made by US Secretary of War Pete Hegseth, Australian Defence Minister Richard Marles and British Defence Secretary Wes Streeting in a joint statement issued on 26 October in the United States and dated 27 October in Australia.

The three governments also confirmed that another US submarine maintenance period would begin in Australia later this week.

Building the AUKUS rotational force

Submarine Rotational Force-West, or SRF-West, is intended to accommodate up to four American nuclear-powered attack submarines and one British submarine on a rotational basis at HMAS Stirling, near Perth.

The vessels will not be permanently based in Australia.

Instead, the arrangement is designed to establish a sustained allied submarine presence while helping Australian personnel develop the technical, operational and regulatory skills needed to support their own future fleet.

SRF-West forms part of AUKUS Pillar I, under which Australia plans to acquire conventionally armed, nuclear-powered submarines, including US-built Virginia-class vessels from the early 2030s.

The rotational force is therefore intended to serve both an operational role and a training function.

Maintenance work already under way

Australia has been progressively expanding its ability to sustain allied nuclear-powered submarines.

In 2024, Australian personnel participated in maintenance work on an American nuclear-powered submarine at HMAS Stirling.

A further maintenance period involving USS Vermont took place in 2025, giving Australian defence personnel and industry workers additional experience supporting a Virginia-class submarine.

Britain's HMS Anson visited Western Australia in February 2026 for a maintenance activity involving a Royal Navy nuclear-powered submarine.

These visits are intended to develop the infrastructure, workforce and procedures required for sustained submarine operations.

Australia is also investing in upgrades at HMAS Stirling, including berthing facilities, shore power, training infrastructure and emergency response capabilities.

Operational and strategic significance

The designation of USS Colorado provides the first named vessel for the rotational force, moving the programme closer to regular submarine operations in Western Australia.

That matters for AUKUS because Australia will need to demonstrate the ability to maintain and support nuclear-powered submarines before acquiring its own vessels.

It also gives US and British submarines additional access to sustainment facilities in the Indo-Pacific.

The partner governments said activities would comply with relevant international agreements and non-proliferation obligations.

The submarines are nuclear-powered but conventionally armed, a distinction central to Australia's AUKUS arrangements.

The next milestones will be the completion of further maintenance activities, continued infrastructure development at HMAS Stirling and the arrival of USS Colorado in 2027.