The fleet will be built in Adelaide, with the new AUKUS partnership to determine the way forward in the next 18 months, aiming at China, the rising power in the Indo-Pacific.

 Australian Prime Minister Scott Morrison said that when Australia had made its last submarine deal in 2016 with Naval Groups, it could not build and operate a nuclear-powered submarine.

“It wasn’t on the table for a range of reasons, so the decision we have made to not continue with the Attack-class submarine and to go down this path is not a change of mind. It’s a change of need,” he said.

 Morrison made the announcement early on. Thursday in Canberra during a virtual address with Joe Biden and Boris Johnson.

“The goal has remained the same.”

Mr Morrison said developments since 2016 had made not only a nuclear-powered submarine fleet feasible for Australia but also a strategic necessity.

Mr Morrison said the government would also commit to enhancing its long-range strike capability, including Tomahawk cruise missiles for Australian Hobart-class destroyers and extended air-to-surface ranges for Australia’s jets.

“We have increased our defence spending as a share of our economy to over two per cent ahead of time, and we will have to keep pressing forward,” he said.

He said Australia’s Collins-class submarines remained among the most high-functioning “conventional” vessels in the world.

Mr Morrison said he had informed French defence contractor Naval Group and President of France Emmanuel Macron to discontinue the Attack-class program in Adelaide.

“I want to stress that France remains an incredibly important partner in the Pacific,” he said.

The United States’ decision to push France aside from a deal, it had signed with Australia to procure submarines shows a lack of coherence when the two allies are facing common challenges in the Indo-Pacific region, France said on Thursday in response.

Mr Morrison has reassured workers involved with the French submarine program that they would need them.

One source said the dramatic move would justify the shift to nuclear technology in light of the changing strategic circumstances as China becomes more aggressive in the region.

As an interim step, there were suggestions that the US was planning to operate some of its Virginia class nuclear-powered submarines out Perth’s naval base, HMAS Stirling.

The British government, which also operates nuclear-powered submarines are expected to support Australia with locally reactor technology.