UK and Australia sign ‘historic’ 50-year Geelong Treaty for SSN-AUKUS program

July 28, 2025, by Fatima Bahtić

Australia and the United Kingdom (UK) have signed the bilateral Nuclear-Powered Submarine Partnership and Collaboration Treaty (the Geelong Treaty) in Geelong, Victoria.

As informed, the agreement was inked on July 26, 2025, by Richard Marles, Deputy Prime Minister and Minister for Defense, Australia and John Healey, Secretary of State for Defense, United Kingdom.

According to the partners, the Geelong Treaty is a historic agreement, the commitment for the next 50 years of UK-Australian bilateral defense cooperation under AUKUS Pillar I.

A joint statement released by the UK and Australia said that the treaty will enable comprehensive cooperation on the design, build, operation, sustainment, and disposal of our SSN-AUKUS submarines.

Furthermore, it will support the development of the personnel, workforce, infrastructure and regulatory systems required for Australia’s SSN-AUKUS program, as well as support port visits and the rotational presence of a UK Astute-class submarine at HMAS Stirling under Submarine Rotational Force – West.

The treaty also builds on the ‘strong foundation’ of trilateral cooperation between Australia, the UK and the United States, advancing the shared objectives of the AUKUS partnership. It will enable the development of SSN-AUKUS and resilient trilateral supply chains, it was highlighted.

Together with the trilateral AUKUS Naval Nuclear Propulsion Agreement (ANNPA), the treaty will enable Australia and the UK to deliver a modern undersea capability through the SSN-AUKUS program.

The countries aim to support stability and security in the Euro-Atlantic and Indo-Pacific regions for decades.

AUKUS is intended to strengthen the ability of each government to support security and defense interests, building on longstanding and ongoing bilateral ties. It was signed in September 2021. Under the deal, Australia plans to build at least eight nuclear-powered submarines, while the UK intends to build up to 12 new conventionally armed, nuclear-powered submarines.