SSN-AUKUS concept design, which will be developed by the Royal Navy and Royal Australian Navy. The design for the nuclear-powered attack boat will be used by both services. Royal Navy photoAustralia and the U.K. on Saturday signed a 50-year bilateral treaty furthering the two countries’ sharing of nuclear propulsion technology under the AUKUS agreement.
The treaty will enable comprehensive cooperation on the design, build, operation, sustainment and disposal of the AUKUS submarines, according to a joint statement. As part of the agreement, the Royal Navy and Royal Australian Navy are set to develop a shared design for a nuclear-powered attack boat that will be used by both services.
The treaty will also facilitate the development of the personnel, workforce, infrastructure and regulatory systems required for Australia’s submarine program, as well as support port visits and the rotational presence of a U.K. Astute-class submarine at HMAS Stirling Royal Navy base under Submarine Rotational Force – West.
“Together with the ANNPA (AUKUS Naval Nuclear Propulsion Agreement), the treaty will enable Australia and the U.K. 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 our two nations, create thousands of jobs, build our respective submarine industrial bases and supply chains, and provide new opportunities for industry partners,” the statement read.
The signing of the bilateral treaty comes as the Pentagon reviews its role in the partnership to ensure it aligns with President Donald Trump’s priorities. The agreement, which was created in 2021, fostered the sharing of U.S. and U.K. technology to help Australia build a nuclear-powered submarine fleet. The review is expected to be complete in the fall, the Defense Department said this week.
The defence ministers of both Australia and the U.K. stressed Saturday’s treaty signing was not an alternate agreement for the two nations to process independently should the U.S. choose not to participate. The signing, they said, had long been planned and was formed as part of AUKUS Pillar 1.
“Both our nations, Australia and the U.K. welcome the review because we see this as a chance for a new administration to renew their commitment to AUKUS, and that’s what we expect. And any sort of hypotheticals that you suggest simply aren’t part of the picture,” U.K. Secretary of State for Defence John Healey said Friday.
Healey and Australian Defence Minister Richard Marles signed the bilateral Nuclear-Powered Submarine Partnership and Collaboration Treaty during the UK-Australia Defence Ministers’ meeting in Geelong, Australia. The two held a joint press conference with Australian Foreign Minister Penny Wong and U.K. Secretary of State for Foreign, Commonwealth and Development Affairs David Lammy following the Australia-UK Ministerial Consultations (AUKMIN) held in Sydney. The four ministers on Sunday visited Royal Navy aircraft carrier HMS Prince of Wales (R09) in Darwin where the carrier was docked on a port visit.
The U.K. government, as part of the Strategic Defence Review 2025, announced in June that up to 12 SSN-AUKUS submarines will be built, entering service from the late 2030s. Australia plans to have its first SSN-AUKUS built in Australia delivered in the early 2040s. The number of SSN-AUKUS that Australia will operate has not yet been decided upon, as it will be dependent on both the number of Virginia-class submarines that Australia is able to acquire under AUKUS and the decision of future Australian governments.
Australia is seeking to acquire a total force of eight nuclear-powered attack submarines. The acquisition of three to five Virginia-class submarines is an interim solution until SSN-AUKUS enters service.
However last week, the nominee to lead the U.S. Navy told Congress the U.S. industrial base must double its attack submarine output for America to meet its obligations under the AUKUS agreement with Australia and the United Kingdom, USNI News reported.
“We do have to understand whether or not the industrial base can produce the submarines required so that we can make good on the actual pact that we made with the U.K. and Australia, which is around 2.2., 2.3 Virginia-class submarines per year,” Adm. Daryl Caudle told senators. “That’s going to require a transformational improvement, not a 10 percent improvement, not a 20 percent, a 100 percent improvement.”
The industrial base currently builds about 1.3 attack boats per year.