Australia, UK to Sign 50-Year Treaty for Nuclear Submarines

By Swati Pandey

Jul 24, 2025 (Bloomberg) –Australia and the UK will sign a landmark 50-year defense treaty on Saturday to underpin the construction of nuclear-powered submarines, senior ministers said following high-level talks in Sydney. 

Framed as the most consequential bilateral agreement since Australia’s Federation in 1901, the pact underscores deepening defense ties between the historic partners against a backdrop of mounting global geopolitical volatility. 

Both sides stressed that the treaty doesn’t impact the Aukus security partnership between Australia, the UK and the US — currently under review by the Trump administration. 

Instead, the bilateral agreement, which will be signed in Geelong near Melbourne, “will very much underpin the development of Aukus,” Australia’s Defense Minister Richard Marles told a press conference next to Sydney Harbor on Friday. “It is a profoundly important treaty that we will sign tomorrow.”

Friday’s meeting is part of the Australia-United Kingdom Ministerial Consultations (AUKMIN). Marles and Foreign Minister Penny Wong are hosting UK Foreign Secretary David Lammy and Defence Secretary John Healey. 

The deal is expected to be worth up to £20 billion ($27 billion) to the UK in exports over the next 25 years, the UK’s Foreign Office said in a statement on Friday. 

The Times of London reported that under the deal, the UK will build up to a dozen attack submarines with both the Royal Navy and the Australian Navy operating the SSN-Aukus. It said the agreement is part of an effort to persuade the US to stick with the Aukus accord. 

Read more: What’s at Stake If Trump Scraps Aukus Security Pact: QuickTake

More than 21,000 people will work on the conventionally armed, nuclear-powered Aukus submarine program in the UK at its peak, the Foreign Office said. “This historic Treaty confirms our AUKUS commitment for the next half century,” Healey was quoted in the statement as saying. 

Under the Aukus agreement signed in 2021, the US and the UK agreed to collaborate on providing Australia with a fleet of nuclear-powered submarines to ramp up Canberra’s defense capabilities in the face of growing strategic competition with China in the Indo-Pacific.

Both sides said they welcomed the US review as a chance to renew the Trump administration’s commitment to Aukus. 

“We’re really confident about the progress of the Aukus project and the progress in respect of all three countries,” Marles said.

Under the terms of Aukus, Washington is initially due to sell a fleet of Virginia-class submarines to Canberra, with the first vessels expected to arrive in the early 2030s. The UK and Australia will then collaborate on designing and building a new model of nuclear-powered submarines known as the SSN-Aukus, with the first expected to be ready in the early 2040s.

However, the Pentagon has launched a review of the pact as the Trump administration looks to shift more responsibility to allies and ensure the US’s supply of warships. The review is aimed at making sure that allies contribute more to collective security and that America’s defense industrial base can meet its domestic needs.

On Sunday, the Australian and British defense and foreign ministers will visit the northern city of Darwin to observe the deployment of a UK Carrier Strike Group as part of Exercise Talisman Sabre 2025.

© 2025 Bloomberg L.P.

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