US to send first nuclear submarine USS Colorado to a base in Western Australia in late 2027

First submarine of the rotational force has been designated

The Pentagon has designated the nuclear attack submarine USS Colorado as the first American submarine to join the rotational force in Western Australia. The Virginia-class submarine, 115 meters long and armed with land-attack cruise missiles and modern torpedoes, will arrive at the new Australian base at the end of 2027, officials said on Tuesday, as reported by AFP.

What the force entails

The rotational nuclear submarine force, known as Submarine Rotational Force-West, will be based at the HMAS Stirling naval base in Western Australia. Under the plan, the base will be able to host up to five attack submarines — four American and one British — on a rotational basis. The three countries said the force will help Australia prepare to operate and maintain its own nuclear-powered submarines, while also supporting allied deployments and maintenance.

Significance within AUKUS

In a joint statement, the allies called the deployment a “significant milestone” in strengthening trilateral deterrence in the Pacific under the AUKUS defense pact, which is seen as a response to China's military buildup in the region. Australian Defense Minister Richard Marles told News24 that the rotational submarine force is the first “truly major milestone” of the agreement and confirmed that the program is on schedule: “American personnel are already at HMAS Stirling and are preparing the site.”

Context and scale of the program

Australia does not allow foreign military bases on its territory, but it hosts US Marines for six months a year for exercises in the northern city of Darwin — the rotational format of the submarine force follows the same approach. The AUKUS submarine program is at the core of Australia's defense strategy; according to government projections, its cost could reach US$235 billion over 30 years.