Australia and the United Kingdom sign AUKUS Pillar 1 Treaty

Australia and the United Kingdom have signed the bilateral Nuclear-Powered Submarine Partnership and Collaboration Treaty (the Geelong Treaty) at the UK-Australia Defence Ministers’ Meeting in Geelong, Victoria. The Geelong Treaty is a commitment for the next 50 years of UK-Australian bilateral defence cooperation under AUKUS Pillar I, says Defence in statement.

The Treaty was signed on 26 July 2025 by the Honourable Richard Marles MP, Australia’s Deputy Prime Minister and Minister for Defence and the Right Honourable John Healey MP, the UK Secretary of State for Defence.

The Geelong Treaty will enable comprehensive cooperation on the design, build, operation, sustainment, and disposal of SSN-AUKUS submarines, says Defence. It will support the development of the personnel, workforce, infrastructure and regulatory systems required for Australia’s SSN-AUKUS programme, as well as support port visits and the rotational presence of a UK Astute-class submarine at Fleet Base West under Submarine Rotational Force – West.

The Treaty builds on the strong foundation of trilateral cooperation between Australia, the UK and the United States, advancing the shared objectives of the AUKUS partnership, Defence adds. It will enable the development of SSN-AUKUS and resilient trilateral supply chains.

Importantly, the Geelong Treaty is consistent with Australia’s and the UK’s respective international nuclear non-proliferation obligations, including under the Treaty on the Non-Proliferation of Nuclear Weapons, the South Pacific Nuclear Free Zone Treaty and its Protocols, and Australia’s safeguards agreements with the International Atomic Energy Agency, and the trilateral AUKUS Naval Nuclear Propulsion Agreement (ANNPA).

Together with the ANNPA, the Treaty will enable Australia and the UK to deliver a cutting-edge undersea capability through the SSN-AUKUS programme, and in doing so support stability and security in the Euro‑Atlantic and the Indo-Pacific for decades to come, drive defence as an engine for growth across the two nations, build the two countries’ respective submarine industrial bases and supply chains, and provide new opportunities for industry partners.