Will Australia have to pay more for AUKUS under Trump?

How will a Trump presidency disrupt the terms of the AUKUS nuclear submarine pact?

It's unlikely a change in administration will stir Washington's appetite to rebuff China's rapid militarisation in the Indo-Pacific.

But experts have speculated Trump will demand Australia to commit more funding to the overall costs of the deal, which will see Australia purchase at least three Virginia class nuclear-attack submarines by the 2030s.

Former chief of the army Peter Leahy says he is confident AUKUS will endure after Trump's return but is worried its slow pace will leave Australia vulnerable in the short term.

"We used to think we had about 10 years; my concern is that while we're providing for future capabilities, I don't think we're proving the focus for a need for an emergency or emergency response," Professor Leahy says.

"I think where we are at the moment and the work that's done by Defence is the right direction, but whether or not it's going to solve the problem, which is a problem of social cohesion and attitude of those of military service age, that's the area that seems to worry me."

Australia has spent billions towards its plan to acquire at least three second-hand attack submarines from the US and is investing about US$3 billion to support America's shipbuilding industry.

The US Navy estimates its submarine production line is 20 years behind schedule, hovering around a production rate of 1.1 to 1.2 boats per year.

The most senior officer running the US' domestic attack submarine program, Rear Admiral Jonathan Rucker, told an industry event in November the navy was not on track to meet its immediate 2025 target.

Professor Leahy says there's ultimately very little Australia can do if Trump convinces Congress to ask allies to renegotiate its spending commitments.

"We've got a defence policy of deterrence," he says.

"We're not capable of doing it ourselves; we need support from others, and without the United States, I think we're vulnerable. If that means the US wants more out of us, in terms of budget and capability, I don't think we have any other option."

Shadow defence spokesman Andrew Hastie says the federal government will have to make some hard choices if Trump asks for more out of the alliance.

He expects the Republican leader to take a transactional approach to the AUKUS deal, meaning Australia will need to increase its diplomatic influence across the wider US bureaucracy.

"We can't rely upon the tired old talking points. We've actually got to demonstrate what we're bringing to the alliance, and I think we've got a very good story to tell," the former army officer says.

"I think the Americans are doing very well with the alliance, and so at the heart of AUKUS is a quid pro quo."

Mr Hastie said during a recent trip to the US he noted a lack of engagement in Congress around other elements of the deal, most notably Australia's plans to host US-owned vessels in Western Australia.

"I think we need to really assert that we are effectively working with the US to give them prime real estate in Perth. They'll be a squadron of US submarines operating out of HMAS Sterling by 2027," he says.

"So questions around further funding into the US industrial base - that's something we can take on a case-by-case basis - but I think the first take for us is to demonstrate the value we're adding on our side of the ledger."

Despite Trump having never said anything publicly about AUKUS, both former prime minister Scott Morrison and Defence Minister Richard Marles have gone on the record to suggest he would support the agreement.

In a recent interview, the defence industry minister Pat Conroy said there was strong bipartisan support for AUKUS in Washington, declaring it would survive regardless of who won power over the coming decades.

"It's in the national interest and AUKUS will survive changes of government across all three countries," he told ABC.

Director of the international security program at the Lowy Institute Sam Roggeveen says there's every indication to suggest Trump would give Australia fewer submarines if it was in the US' best interest.

"We have to weigh the fact that Trump is famously unpredictable. I do think it's important that in Trump's term, none of the major spending items or decisions are going to come up for grabs," he said.

"There will be a few decisions that will need to be made in the next term in order to progress that."

Mr Roggeevan argues the presence of an AUKUS fleet operating near China's coast makes Australia a bigger target for Beijing's military aggression.

He says a far more effective long-term defence strategy would be to exploit the vast distance separating the two nations.

"It's often forgotten that Beijing is closer to Berlin than it is to Australia - the big distance is our best asset," he says.

"We are spending billions of dollars in shipbuilding, and at the end of that process, it essentially serves as a way to overcome that distance.

"We are trying to bring Australia and China closer together when we should be keeping them further apart."

During a media briefing in Canberra last month, Chinese Ambassador Xiao Qian told reporters there should be "no reason" Australia's relations with China would be tampered with under the Trump administration.

His comments came after the US president-elect announced he would impose significant new trade tariffs on China after taking office in January.

During a speech to the national press club, outgoing US ambassador Caroline Kennedy acknowleged both the US and Australia's respective relationships will be deeply reshaped over the life of the AUKUS deal.

She said the nuclear submarine plan was an "existential investment" in Australia's sovereignty and flagged it would be difficult to predict how Trump would operate during his second term.

"Everyone knows the history of the 21st century is going to be written in the Indo-Pacific," she said in a farewell address.

"And I think AUKUS, in a critical way, it's already having a huge impact in deterrence and in keeping the peace and stability."