Australia's former top diplomat in Washington is "nervous" about the promised delivery of nuclear-powered submarines from the US, while cautioning against giving the Americans an exit out of the deal through a back-up plan.
Under the AUKUS partnership, Australia is set to acquire three Virginia-class submarines in the early 2030s, before a new fleet is built for delivery from the 2040s.
Former treasurer Joe Hockey, who served as ambassador during the first Trump administration, said the relationship between Washington and Canberra remained strong, but submarine production in the US wasn't keeping pace.
"For the first time, I'm a little nervous about the Virginias, and that's after a few conversations on the Hill," he told the National Press Club on Tuesday.
"Not because of relationship at all ... the US just has not got the production of the Virginia up to speed."
Asked if he was concerned the nuclear-powered boats won't arrive on time, Mr Hockey said the risk was increased.
"We need again to have a full court press on the ground in Washington," he said.
"It's a manageable risk at this stage, but every day counts."
Pressed on the possibility of an alternate plan, Mr Hockey said Australia needed a reinforcement of plan A.
"Don't give them plan B," he said.
Security experts have long raised concerns about the capacity of the US to sell boats to Australia as they fell behind on production.
While Japan has been put forward as a potential partner should the deal fall over, the Albanese government has shut down the suggestions.
The coalition has pointed to Australia's limited budget and smaller defence force as reasons why the nation couldn't juggle multiple programs at the same time.
Chief of Navy Mark Hammond, who will soon become the new defence force chief, said the evidence showed AUKUS was succeeding.
"I think we should stop politicising ambitious, challenging programs with the partners being completely transparent about the risks and the challenges," The Nightly reported from a security conference in Perth.
