Australia’s navy is overhauling its submarine fleet by acquiring at least six bigger and nuclear-powered vessels from the United States under a defense alliance with the US and the United Kingdom dubbed Aukus.

US President Joe Biden announced on Monday the ambitious submarine refleeting program that will cost Canberra at least $40 billion in the first decade during an event in a San Diego, California naval base attended by Australian Prime Minister Anthony Albanese and UK Prime Minister Rishi Sunak.

Three conventionally armed, nuclear-powered Virginia class vessels will be sold “over the course of the 2030s,” with the “possibility of going up to five if that is needed,” Biden’s national security advisor, Jake Sullivan, said.

Britain and Australia will then embark on building a new model, also nuclear-powered and carrying conventional weapons, dubbed the SSN-Aukus. This will be a British design, with US technology, and “significant investments in all three industrial bases,” Sullivan said.

Compared to the Collins-class submarines due to be retired by Australia, the Virginia-class US subs is almost twice as long and carries 132 crew members, not 48.

The submarines armed with cruise missiles but without nuclear weapons is part of Aukus’ efforts to push back against Chinese military expansion in the Pacific region.

China has built a sophisticated naval fleet and turned artificial islands into offshore bases in the Pacific.

Albanese stressed that Australia was now only the second country, after Britain, to be granted access to US naval nuclear secrets.

A senior US official said that the British navy should get its “state of the art” SSN-Aukus vessels in the late 2030s and Australia only in the early 2040s.

In the meantime, Australian sailors, engineers and other personnel will be training with their US and British partners to acquire expertise, while British and US submarines make regular visits to Australian ports.

China warned that Aukus risks setting off an arms race and accused the three countries of setting back nuclear nonproliferation efforts.

The sale of submarines “constitutes a severe nuclear proliferation risk, and violates the aims and objectives of the Non-Proliferation Treaty,” Wang Wenbin, China’s foreign ministry spokesperson, said.

WITH AFP