Australia and the United Kingdom have signed a landmark 50-year defence treaty under the AUKUS alliance, even as the United States undertakes a review of its commitment to the trilateral pact.

Australian Deputy Prime Minister and Defence Minister Richard Marles, along with UK Defence Secretary John Healey, signed the Geelong Treaty—a formal agreement under AUKUS Pillar I—during their meeting in Geelong, Victoria on Saturday.

“The Geelong Treaty is a historic agreement, committing the UK and Australia to bilateral defence cooperation for the next 50 years,” the ministers said in a joint statement.

The treaty paves the way for collaboration on the design, construction, operation, and maintenance of nuclear-powered SSN-AUKUS submarines. It also supports workforce development, infrastructure, regulatory systems, and the rotational deployment of the UK’s Astute-class submarines at HMAS Stirling under the Submarine Rotational Force-West.

This agreement comes amid uncertainty from the United States, where the Department of Defence has initiated a review of the AUKUS pact to assess its alignment with the “America First” policy.

Despite the review, both Australia and the UK emphasized that the treaty strengthens the trilateral alliance and supports resilient supply chains for nuclear submarine development.

AUKUS was originally launched in September 2021 by the US, UK, and Australia to enhance Indo-Pacific security through the sharing of nuclear-powered submarine technology. However, Australia’s role as a non-nuclear-weapon state has raised global concerns about nuclear proliferation and regional stability.

According to reports, the Australian government recently made its second $800 million AUD payment to the US as part of the submarine procurement deal.