The US, UK and Australia have unveiled details of their plan to create a new fleet of nuclear-powered submarines, aimed at countering China's influence in the Indo-Pacific region.
Under the Aukus pact Australia is to get its first nuclear-powered subs - at least three - from the US.
The allies will also work to create a new fleet using cutting-edge tech, including UK-made Rolls-Royce reactors.
Beijing has strongly criticised the significant naval deal.
Its foreign ministry on Tuesday accused the three nations of "walking further and further down the path of error and danger".
China's UN mission had earlier also accused the Western allies of setting back nuclear non-proliferation efforts.
But US President Joe Biden said the deal was aimed at bolstering peace in the region and stressed the submarines would be "nuclear-powered, not nuclear-armed".