Navy Submarine Arrives in Western Australia for Scheduled Maintenance Period

The submarine USS Colorado arrived at HMAS Stirling, Australia, yesterday to begin a scheduled, monthlong maintenance period.

The visit marks the fourth submarine maintenance period in Western Australia since the establishment of the Australia, U.K., U.S. trilateral security partnership and highlights ongoing progress under AUKUS pillar one.

The USS Colorado is the sixth nuclear-powered attack submarine to visit HMAS Stirling following the announcement of the AUKUS Optimal Pathway in 2023 and the third to undergo maintenance in Australia in the last 12 months.

The port visits and maintenance periods are part of the pillar one plan to help Australia acquire, operate and maintain its own conventionally armed, nuclear-powered submarine fleet.

Secretary of War Pete Hegseth and his Australian and U.K. counterparts issued a joint statement Oct. 26, naming the USS Colorado as the first U.S. Navy fast-attack submarine assigned to the reactivated Submarine Squadron 3. The boat will help formally establish Submarine Rotational Force – West upon its planned return in late 2027.

Over the coming weeks, more than 30 trained and certified Australian civilian maintenance technicians will perform routine maintenance on a submarine in Western Australia for the first time, working alongside specialists assigned to Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility, Hawaii.

Under SRF-West, up to four U.S. submarines and one U.K. submarine will rotationally operate out of HMAS Stirling. For Australia, the force accelerates its readiness to maintain, operate and sustain nuclear-powered submarines, while affording greater access to the Pacific region, the Indian Ocean and adjacent areas, enhancing regional deterrence and operational flexibility for allied submarines.

"This maintenance period brings us closer to establishing SRF-West," said U.S. Navy Rear Adm. Doug Adams, AUKUS International and Systems director. "Our lead maintenance activity, Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility, is doing a great job ensuring the Australian personnel trained in Hawaii are ready and able to support our submarines."

The maintenance period will demonstrate several new pieces of Australian-built infrastructure. Technicians will use a custom-made metal safety walkway, known as a sail "racetrack." The team will also leverage recent submarine-specific upgrades made to HMAS Stirling's Diamantina Pier and other local solutions, such as a pure water plant, high-pressure air compressor and dehumidifier.

"With each visit, Australia demonstrates new organic capabilities," said U.S. Navy Capt. Jason Pittman, Submarine Squadron 3 commander. "During last year's maintenance period, we successfully delivered pure water from an Australian-designed and built plant and validated the sail racetrack was fit for purpose."

During the U.K.'s maintenance period in February, the squadron validated the high-pressure air compressor and dehumidifier systems. Now, the team is using the racetrack to conduct maintenance, utilizing the pier upgrades, and leveraging a workforce of about three dozen Australian civilian submarine maintenance workers.

"Through these historic port visits, Australia has continued to progress our ability to not just host [nuclear-powered submarines] for longer periods but also deliver maintenance to schedule and get the boats back to sea," said Royal Australian Navy Rear Adm. David Mann, head of the Australian Submarine Agency's Virginia Division.

The U.K.'s Royal Navy will be an active participant in the submarine maintenance period.

"We don't get many opportunities like this," said Stephen Lovegrove, the U.K. prime minister's special representative for AUKUS. "The more the three nations work together to maintain submarines — whether American or British — the faster we'll be able to uplift our Australian partner's knowledge and skills and increase commonality across our submarine forces."

"This maintenance activity represents the ultimate integration of a U.K., U.S. and Australian workforce," Mann said. "Operating as a single team, we are testing our infrastructure, validating our nuclear stewardship processes, and substantially upskilling our naval and civilian workforces. These maintenance periods have been critical to Australia being on track to start SRF-West in 2027."

For the crew of the Colorado, the success of this port visit relies heavily on the close partnership between the boat, Australian partners and shipyard personnel. This joint workforce ensures the submarine remains fully mission-ready for its forward-deployed operations.

"The success of any maintenance period comes down to the people on the deckplates, and the Australian personnel stepping aboard our ship are true professionals," said U.S. Navy Capt. Justin Reeves, USS Colorado commander. "Their technical skill and dedication are exactly what we need to keep this ship in the fight, and it gives us absolute confidence in Australia's ability to support the fleet."