Rishi Sunak has announced in California the details of the UK-US pact to supply Australia with nuclear-powered submarines. Aukus was first-unveiled in September 2021: in the 18 months since, the three nations have agreed that the new fleet will be built in Britain and Australia to British designs. It’s only the second time ever that the United States have shared nuclear submarine technology with its allies, following a similar UK/US deal in 1958.