Australia has backed the right of the US to sail a warship within 12 nautical miles of one of China's artificial islands in the South China Sea.
Defence Minister Marise Payne said all states had a right under international law to freedom of navigation and freedom of overflight, including in the South China Sea.
"Australia strongly supports these rights," she said in a statement.
Nations bordering the South China Sea have made numerous overlapping territorial claims, primarily because of oil and gas deposits.
China claims virtually all of the South China Sea. It inflamed regional tensions when it started building its own islands on disputed reefs, adding airstrips, radar and communications and defence systems, plus troops.
China insists the 12 nautical mile territorial limit applies. The US points to international law, which says it doesn't for artificial islands.
It's long been anticipated the US would test the principles of freedom of navigation.
A US Navy destroyer USS Lassen sailed by one of the land formations claimed by China in the disputed Spratly Islands chain early on Tuesday .
Senator Payne said Australia wasn't involved.
But Australia had a legitimate interest in maintaining peace and stability, respect for international law, unimpeded trade and freedom of navigation and overflight in the South China Sea.
"Approximately sixty per cent of Australia's exports pass through the South China Sea," she said.
"Australia continues to co-operate closely with the US and other regional partners on maritime security."
