US assigns first nuclear-powered sub to Australian base

The Pentagon has assigned the USS Colorado as the first US nuclear-powered attack submarine to join a rotating force to be based in western Australia.

The 377-foot (115-metre) Virginia-Class submarine, armed with land-attack missiles and sophisticated torpedoes, will sail to the new Australian base in late 2027, officials said Tuesday.

The deployment is a "significant milestone" in building up a joint US-Australia-UK deterrence in the Pacific under their AUKUS defence pact, the allies said in a joint statement.

The defence agreement, seen as a response to China's military buildup in the region, aims to equip Australia's navy with a fleet of stealthy nuclear-powered submarines and expand military cooperation between the three allies.

Australia does not permit foreign military bases on its soil, but hosts US Marines for exercises for six months of the year in the northern city of Darwin.

The rotating force of nuclear-powered submarines -- known as Submarine Rotational Force-West -- is to be hosted at a naval base in Western Australia, HMAS Stirling.

The base is projected to host up to five fast-attack submarines -- four from the United States and one from the UK -- on a rotational basis.

It will help Australia prepare for operating and maintaining its own nuclear-powered submarines while supporting its allies' deployments and maintenance, the three countries said.

The rotating submarine force was the first "really big milestone" under the AUKUS agreement, Australian Defence Minister Richard Marles told news channel News24.

"It's on track," Marles said.

"There are American personnel at HMAS Stirling right now readying the site for this."

The AUKUS submarine programme lies at the heart of Australia's defence strategy and could cost up to US$235 billion over 30 years, according to government forecasts.