Australia will receive used nuclear-powered submarines from the US under an amended AUKUS deal, Defence Minister Richard Marles said, citing cost-effectiveness.
The move was announced at the Shangri-La Dialogue in Singapore, where top defence officials and experts from 45 countries met.
Under the 2021 AUKUS deal, Australia was expected to receive at least three Virginia-class submarines within 15 years, but now all three will be in-service vessels from the US Navy stock.
Marles said the decision was "cost-effective" and would simplify supply chain management and operational requirements.
The US Navy has 24 Virginia-class vessels, but American shipyards are struggling to meet production targets.
The AUKUS submarine programme could cost up to $235 billion over 30 years, according to government forecasts.
