The coalition will spend $3 billion to reinstate a fourth squadron of F-35A fighter jets to the Air Force, should the party win the upcoming federal election
The extra squadron would see 28 aircraft added to Australia's fighter jets, boosting the fleet to 100 from 72.
Opposition defence spokesman Andrew Hastie said the extra planes were needed at a time of global uncertainty and would send a clear message to Australia's allies, including US President Donald Trump.
"Today's announcement, which has been in the works for many months, sends a strong signal not just to the region, but also to a critical partner like the US that we're not a free rider," he told Sky News on Sunday.
"(It would signal) we're actually a heavy lifter and we invest to take care of our own security - not be dependent upon the United States all the time."
The $3 billion funds would be used to secure the fourth squadron and the cost of the fighter jets would be negotiated.
Opposition Leader Peter Dutton said negotiations would take place as soon as possible for the defence force to get the jets - if the coalition wins - and they could be delivered in the next five years.
"Only the coalition is committed to backing defence by increasing the current defence budget and providing our ADF with the capabilities they need," he said.
However, the government questioned where the coalition would find the funding for the extra fighter jets in the budget.
Prime Minister Anthony Albanese said there was a lack of detail and attacked the coalition's record on defence investment.
"You can't defend yourself with a media release - what you need to defend yourself is ... assets - and Australia simply can't trust Peter Dutton and his empty promises," Â he told reporters in Sydney.
Mr Hastie and coalition home affairs spokesman James Paterson, who gave interviews on the defence plan on Sunday, "had no idea where the money was going to come from, no timeframes, no outlines of the additional expenditure that will be required for something like that."
The federal government expects defence spending to reach 2.4 per cent of the nation's economic output by 2033/34.
Mr Hastie said the fighter jets would contribute to rebuilding defence force capacity.
"Our defence force has been driven into the ground. Morale is at an all-time low," he said.
"We want a strong country, and given today's dangerous strategic circumstances, we are investing in it so that we can secure the Australian people and our interests."
Mr Hastie said the AUKUS security pact, which will allow Australia to obtain nuclear submarines, was all the more reason for the Australia Defence Force to prioritise spending.
"AUKUS is a massive, multigenerational endeavour. It's a nation-building endeavour. It's going to be expensive," Mr Hastie said.
"If we don't account for the cost, the structural pressure that that will put on our defence budget, ... other capabilities will be cannibalised."
Australia will spend $368 billion to obtain the submarines.
