Former PM Malcolm Turnbull has warned Australia may never get the nuclear submarines it was promised under AUKUS, after a drastic funding decision in the US.

Under the AUKUS agreement, the US will sell Australia at least three, and possibly five, second-hand Virginia-class subs in the early 2030s – the first by 2032.

But production of one submarine has been cut from the proposed US defence budget for 2025, sparking concerns for Canberra’s planned acquisition.

Turnbull said Australia was completely dependent on Washington to acquire the sub and US would always back its own navy if there was a shortage in production.

“The reality is the Americans are not going to make their submarine deficit worse than it is already by giving or selling submarines to Australia, and the AUKUS legislation actually sets that up,” he told ABC radio on Wednesday.

“We are bobbing along as a cork in the maelstrom of American politics.

“The reality is, unless the Americans are able to dramatically change the pace at which they’re producing submarines – and there’s no reason to believe they will be able to do so – we will not ever get the submarines that were promised.”

US defence under-secretary comptroller and chief financial officer Michael McCord said Virginia-class submarines meant to be delivered this year in America were running an average of more than 30 months late.

There are still more than a dozen subs ordered and in production.

The US reportedly must lift its submarine production to two a year by 2028 to even meet its own needs.

To allow for sales to Australia, it needs an annual build rate of 2.33. But its for the past decade has been just 1.3 subs a year.

Former senator, and one-time submariner, Rex Patrick took aim at the AUKUS arrangements on Wednesday.

“We’re pouring $4.7 billion into US shipyards to get the US sub production rate from 1.4 subs per annum to 2.3. If, after we’ve handed over our money, they only hit 2 boats per annum, the US fulfil their sub needs and we get NO subs at all,” he wrote on X.

“Even if the 2.3 target is hit, the President can renege if transferring the subs is not ‘consistent with US foreign policy and national security interest’. Those ‘Humpty Dumpty’ words can mean just what the President choses them to mean; nothing more, nothing less.”

President Joe Biden’s budget request for 2025 also includes US$11 billion ($16.7 billion) for additional investment over the next five years for the domestic submarine industry.

“We’ve already had some beginnings of submarine industrial base investments … It was a priority in last year’s budget, which, again, we don’t have that money yet, so that’s a problem,” McCord said.

Australia will also contribute $3 billion to the US submarine industry to help increase production rates.

McCord said spending money to prop up the industry rather than spending it on another submarine was a smarter investment, as the US pushed to boost its production rate to two submarines a year.

“We thought that going a different direction was our best move in that,” he said.

But Defence Minister Richard Marles said that despite the financial decisions, Australia, Britain and the US remained committed to the AUKUS pact under which the subs would be delivered.

“All three AUKUS partners are working at pace to integrate our industrial bases and to realise this historic initiative between our countries,” he said.

Rank and file Labor members have come out against the AUKUS agreement, questioning why Australia would send billions of dollars to prop up the US production line.

Labor Against War branded the US budget cut to the Virginia-class a “potential lethal blow to AUKUS”.

– with AAP