“It enhances our ability in the subterranean space, but also our allies and partners. This is not a mission in the Indo-Pacific that America can undertake by itself. It has to be robust allies and partners, technology-sharing, and subs are a huge part of it.”

Leaders of Australia, UK and the US who signed the AUKUS deal called it the most strategically important partnership in decades, adding the goal is to promote a free and open Indo-Pacific that is secure and stable.

Hegseth said he “sure hopes” his country could fulfil the deal as Marles described the $US3 billion injection as a “a very unique and significant step” in the alliance.

Australia’s military budget is expected to rise to 2.3 per cent of GDP by 2034, putting it in line with current spending by the UK and ahead of France and China.