The Virginia-class submarine, USS Vermont (SSN 792), has departed HMAS Stirling following a landmark package of maintenance work.
The Submarine Maintenance Period (SMP) was the first time a US nuclear-powered submarine (SSN) has undergone a maintenance period in Australia without a US support ship, achieved through the combined efforts of Australian and US uniformed and civilian personnel.
Additionally, the UK had a large contingent of military and civilian personnel on-hand to observe the planning and maintenance work ahead of a planned Astute-class SSN visit in 2026.
Over the past four weeks, Royal Australian Navy personnel and ASC workers have partnered with their US counterparts to complete more than 160 maintenance tasks-strengthening Australia's workforce and industrial capacity to sustain nuclear-powered submarines.
Among the innovations delivered was a world-first mobile pure water plant, designed and manufactured by Western Australian companies MAK Water and Diverse Welding, meeting stringent US and UK standards.
Australia's sovereign partner for the sustainment of nuclear-powered submarines, ASC Pty Ltd, played an integral role during the maintenance period.
ASC workers and suppliers provided critical support, including installation of a bespoke submarine sail "racetrack" platform, staging and cranage services, and stewardship training exercises simulating radiological safety procedures.
No radiological material was transferred ashore during this maintenance period.
ASC's involvement in this maintenance period reflects the phased approach to building Australia's sovereign sustainment capability.
Twenty ASC personnel currently training at Pearl Harbor Naval Shipyard returned to Australia and integrated with more than 100 staff from the Pearl Harbor Naval Shipyard Maintenance team to deliver the SMP.
There are over 200 Australian Defence Industry members currently undergoing specialised SSN sustainment training at the Pearl Harbor Navy Shipyard and Intermediate Maintenance Facility.
Increased and longer port visits by US and UK submarines are integral to developing Australia's ability to operate, maintain and safely steward our future conventionally-armed SSNs.
This SMP is the second of two US SSN submarine port visits to Australia in 2025, following the arrival of USS Minnesota (SSN 783) in February.
Through these visits and maintenance periods, and with our personnel working side by side to transfer necessary knowledge and skills, AUKUS partners are accelerating progress to establish Submarine Rotational Force - West.
The next port visit to HMAS Stirling will occur in the first half of 2026 with a maintenance period scheduled for a visiting UK Astute-class submarine.
