They've agreed to share nuclear submarine intel.
The UK, US and Australia have formed a defence partnership - and agreed to share nuclear submarine secrets.
The agreement - known as Aukus - comes at a time of growing concern over China.
The Chinese embassy in the US has responded with a statement saying the countries should "shake off their Cold-War mentality."
The Australian Prime Minister Scott Morrison says there's a key priority.
#UPDATE Australian PM Morrison says the country will acquire long-range US Tomahawk missiles, as it strengthens military defences in the face of a rising China.
— AFP News Agency (@AFP) September 16, 2021
"We will be enhancing our long-range strike capability including Tomahawk cruise missiles..." pic.twitter.com/Rp6Uyq9R98
