Aukus: nuclear submarines deal will cost Australia up to $368bn

The program is forecast to cost $268bn to $368bn between now and the mid 2050s, most of it beyond the first four-year budget period.

The first Australian-built nuclear-powered submarines, fitted with vertical launch systems to fire cruise missiles, are due to enter into service in the early 2040s.

From 2027 at the earliest, the UK and the US plan to establish a rotational presence of one UK Astute class submarine and up to four US Virginia class submarines at HMAS Stirling near Perth, Western Australia.

Beginning in the early 2030s, the US intends to sell Australia three Virginia class submarines, with the potential to sell up to two more if needed, pending approval from the US Congress.

Administration officials said the US would announce an investment of US$4.6bn in its own submarine industrial base. While these would be American funds, Australia would also make a sizeable contribution.

The funding for US domestic production could be a point of tension in Australia at a time when the budget is facing pressure on multiple fronts.