U.S. Navy Selects USS Colorado as First Nuclear Submarine for Australia's AUKUS Rotational Force

The Pentagon has designated the USS Colorado (SSN 788) as the first American nuclear-powered submarine to join a new rotational force based in Australia. The Virginia-class fast-attack vessel will deploy to HMAS Stirling in Western Australia starting in late 2027.[1][3]

This deployment anchors Submarine Rotational Force-West (SRF-West), a central component of the AUKUS security pact between the United States, the United Kingdom, and Australia. The initiative is designed to build Canberra's capacity to operate and maintain a sovereign fleet of conventionally armed, nuclear-powered submarines.[1][7]

Once fully operational, SRF-West is projected to host up to four U.S. Virginia-class submarines and one British fast-attack submarine on a rotational basis. The continuous presence is intended to project allied undersea power in the Indo-Pacific while actively training Australian crews.[6][7]

The USS Colorado announcement precedes a scheduled U.S. Submarine Tendered Maintenance Period beginning later this week at the Australian base. The operation involves complex repair and sustainment work conducted outside of domestic U.S. shipyards to test regional logistics.[6][7]

Preparing the Infrastructure

To support the influx of nuclear-powered vessels and personnel, the Australian government is executing an $8 billion AUD expansion of HMAS Stirling. The naval base, located on Garden Island near Perth, is undergoing extensive wharf upgrades and logistical improvements.[2]

The U.S. Navy established Naval Support Activity Stirling at the site in June 2026 to facilitate the transition. The command provides dedicated services and administrative programs for American service members, civilian contractors, and their families who will be stationed in Western Australia.[3]

The maintenance periods rely heavily on submarine tenders like the USS Emory S. Land, which previously deployed to HMAS Stirling to train Australian personnel. These joint exercises allow Royal Australian Navy sailors to perform hands-on mechanical repairs under American supervision.[1][3]

Defense officials stated the upcoming maintenance period is intended to demonstrate Australia's growing technical capacity to sustain American and British nuclear-powered vessels. Mastering these maintenance protocols is a strict prerequisite for Australia to safely operate its own nuclear fleet.[6][7]

The AUKUS Pathway

The rotational force represents the second phase of the AUKUS "Optimal Pathway" established in March 2023. The first phase involved increased port visits, while the third phase will see the U.S. sell at least three Virginia-class submarines to Australia in the early 2030s.[2]

The final phase involves building a new class of submarines, SSN-AUKUS, based on a British design integrated with American combat systems. These vessels will be constructed in both the U.K. and at a new shipyard in South Australia starting in the late 2030s.[2]

The total AUKUS submarine program is projected to cost Australia up to $368 billion AUD over the next three decades. As part of the agreement, Canberra is also investing approximately $4 billion AUD into the U.S. and U.K. submarine industrial bases to alleviate production bottlenecks.[2]

The integration of uncrewed undersea vehicles represents a parallel effort to rapidly expand maritime domain awareness. These autonomous systems will operate alongside the Virginia-class submarines, extending their sensor reach and providing a cost-effective layer of defense against adversary incursions.[3]

Vessel Capabilities

The USS Colorado, commissioned in 2018, is a Block III Virginia-class fast-attack submarine. Displacing 7,800 tons and measuring 377 feet in length, the vessel carries a crew of approximately 135 officers and enlisted sailors.[1][3]

The Block III design features a revised bow and two large-diameter Virginia Payload Tubes, each capable of launching six Tomahawk cruise missiles. The submarine is also equipped with four 21-inch torpedo tubes for Mark 48 advanced capability torpedoes.[1]

Beyond its kinetic payload, the USS Colorado is designed to conduct covert long-term surveillance of littoral waters and support special operations forces. Its advanced acoustic sensors and fiber-optic masts allow the crew to gather intelligence without exposing the vessel to hostile radar.[1]

"SRF-West will accelerate Australia’s readiness to own, operate, maintain, and regulate a sovereign, conventionally armed, nuclear-powered submarine capability," the Pentagon said in a joint statement. The statement noted the force will expand maintenance options and sustainment infrastructure across the region.[1][3]

Strategic and Diplomatic Stakes

The deployment framework was solidified on May 30 in Singapore, where U.S. Defense Secretary Pete Hegseth met with Australian Defence Minister Richard Marles and U.K. Defence Secretary John Healey. The officials finalized the operational timelines for the trilateral security partnership.[3][7]

The trilateral partners emphasized that all SRF-West activities will operate under the U.S.-Australia Force Posture Agreement. The operations are designed to comply strictly with the Nuclear Non-Proliferation Treaty and International Atomic Energy Agency safeguards.[6][7]

Operations will also adhere to Australia's commitments under the South Pacific Nuclear Free Zone Treaty, known as the Treaty of Rarotonga. The submarines' reactors use highly enriched uranium that is sealed for the life of the vessel, and they will not carry nuclear weapons.[6]

The success of the rotational force will test whether the U.S. and U.K. industrial bases can support forward-deployed nuclear assets while simultaneously training a foreign partner's workforce. The timeline requires seamless coordination to prevent a capability gap as Australia retires its aging Collins-class submarines.[2][7]