In a sign of the broad and bipartisan support AUKUS enjoys in Congress, Caudle was pressed by Senate Armed Services Committee chairman Roger Wicker a long-serving Mississippi Republican on the need to meet the benchmark and fulfil the AUKUS demands.

Caudle agreed. There needs to be some creativity, some ingenuity, some outsourcing improvements, he said. We need an all-hands-on-deck approach to this to get to the 2.3 submarines per year.

In his written testimony, Caudle told the committee: Current trends are worrying, and should I be confirmed, this issue will have my utmost attention and priority to ensure a productive outcome.

Last week, this masthead revealed Australia had paid a second instalment of about $800 million into the US maritime industrial base, following an initial cheque in February. Prime Minister Anthony Albanese said the payments followed an agreed schedule.

The Pentagon subsequently confirmed to this masthead that the second payment was made in June. Defence Minister Richard Marles has said Australia was aware of the Pentagons AUKUS review weeks before it was publicly revealed on June 11.

Defence Minister Richard Marles (left) said his US counterpart, Pete Hegseth, gave him a heads-up about the AUKUS review.

The Pentagon also declined to reveal how the money would be spent. The Department of Defence will stay in close contact with Australia about any planned expenditure of these funds, a US defence official said. We will not comment otherwise on the status or planned allocation of these investments.

Uncertainty about the future of AUKUS under the Trump administrations America First agenda has prompted some allies of Australia in Congress to increase the pressure on senior officials.

Democratic congressman Joe Courtney, who co-chairs the Friends of Australia caucus, said Australias second $800 million payment underscored the depth of its commitment to AUKUS.

If there are improvements that the review is going to put forward, I think we would embrace them, he said.

Defence Minister Richard Marles, UK Foreign Secretary David Lammy, Foreign Minister Penny Wong and UK Defence Secretary John Healey at Admiralty House in Kirribilli, Sydney on Friday.

But to sort of stop it or retard it would be a huge mistake.

Courtney is also spearheading a push to boost the USs own spending on Virginia-class submarines by $US1 billion ($1.54 billion) next year, saying it would address a shortfall in Trumps proposed budget. The measure is yet to pass through Congress.

In April, Trump signed an executive order aimed at restoring American maritime dominance. However, the shipbuilding unit moved from the National Security Council to the Office of Management and Budget, and its exact role is still unclear.