Melbourne (Agencies) July 25, 2025 — In a historic move to deepen defense cooperation and counter rising geopolitical tensions in the Indo-Pacific, Britain and Australia have announced the signing of a 50-year treaty to jointly build a fleet of nuclear-powered submarines for the Royal Australian Navy. The agreement, set to be formalized on Saturday, marks one of the most significant bilateral defense commitments since Australia’s federation in 1901.
The treaty will underpin the AUKUS trilateral alliance, launched in 2021 by Australia, the United Kingdom, and the United States to bolster regional security in response to China’s expanding military footprint. Under the pact, Australia is expected to acquire at least eight submarines, including three to five second-hand U.S. Virginia-class vessels, while collaborating with Britain to co-develop the next-generation SSN-AUKUS class.
Speaking at the annual Australia–UK Ministerial Consultations (AUKMIN) in Sydney, Australian Deputy Prime Minister Richard Marles and UK Defense Secretary John Healey emphasized the enduring strategic value of the partnership. “It is as significant a treaty as has been signed between our two countries since federation,” Marles stated.
The announcement comes amid uncertainty over the U.S. commitment to AUKUS, as President Donald Trump’s administration conducts a formal review of the pact. Concerns have emerged over delays in U.S. submarine production, potentially jeopardizing the timely delivery of Australia’s first Virginia-class submarine by the early 2030s.
Despite speculation, both Marles and Healey expressed confidence in continued trilateral cooperation. “Australia and the UK welcome the review because we see this as a chance for a new administration to renew their commitment to AUKUS,” Healey said. “Any sort of hypotheticals simply aren’t part of the picture.”
Australia has already paid $1 billion in installments to the U.S. under the AUKUS framework, with the total submarine program projected to cost up to $245 billion.
The treaty coincides with Exercise Talisman Sabre 2025, the largest multinational military drill ever hosted by Australia. Over 35,000 personnel from 19 nations are participating in joint operations across air, land, sea, cyber, and space domains.
A key highlight is the arrival of the British aircraft carrier HMS Prince of Wales in Darwin, marking the first Royal Navy carrier visit to Australia in nearly three decades. The carrier is leading the UK Carrier Strike Group in coordinated drills with U.S. and regional forces.
UK Foreign Secretary David Lammy described the deployment as a “clear signal” of Britain’s commitment to Indo-Pacific stability. “Our determination to keep the Indo-Pacific free and open, and that we stand together, could not be clearer,” he said.
The treaty is expected to generate tens of thousands of jobs across both nations and reinforce long-term industrial collaboration in nuclear propulsion, shipbuilding, and defense technology.