Australia emphatically backed the latest incursion by the United States into the South China Sea and hinted at naval and air missions of its own.
Following Saturday's exercise in which the US guided missile destroyer USS Curtis Wilbur angered Beijing by sailing near a disputed island in the South China Sea, Australian Defence Minister Marise Payne said the US was upholding international law. 
"It is important to recognise that all states have 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 on Sunday.
"Australia has a legitimate interest in the maintenance of peace and stability, respect for international law, unimpeded trade and freedom of navigation and overflight in the South China Sea. Approximately 60 per cent of Australia's exports pass through the South China Sea.
"As we have done for many decades, Australian vessels and aircraft will continue to exercise rights under international law to freedom of navigation and freedom of overflight, including in the South China Sea."
China has been inflaming tensions in the region with its territorial claims over international trade routes, even building artificial reefs and islands to expand those claims.
In a statement, the Pentagon said the USS Wilbur had sailed within 12 nautical miles of Triton Island in the Paracel Islands, to counter "excessive maritime claims of parties that claim the Paracel Islands".
Senator Payne kept open the option of talking a more proactive role to protect its trade routes, saying "Australia continues to cooperate closely with the United States and other regional partners on maritime security".
In   December, Australia backed the US by stepping up flights of a surveillance aircraft, an RAAF P-3 Orion, over the disputed air space, prompting a demand from Chinese naval forces in the waters below to explain itself.
An Australian crewman told the Chinese navy the plane was "exercising international freedom of navigation rights".
The situation was discussed by Prime Minister Malcolm Turnbull and President Obama when they met in Washington two weeks ago and by Mr Turnbull and US Pacific fleet Commander Admiral Harry Harris when they met in Hawaii as the Prime Minister flew home.
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