Prime Minister Malcolm Turnbull says Australia is absolutely committed to freedom of navigation and freedom of flying over the South China Sea.
RAAF aircraft have patrolled over the South China Sea for more than 30 years and will continue to fly wherever international law permits including near territory claimed by Beijing, a senior military commander insists.
Vice Admiral David Johnston, head of defence joint operations, says a RAAF Orion was clearly close enough to one of China's reclaimed islands late in November to prompt a radio challenge from a Chinese warship.
That incident was monitored by a BBC media crew in another aircraft, prompting claims the RAAF was patrolling more often near disputed territory to send a message to China.
Vice Adml Johnston wouldn't say just how close the RAAF aircraft was to Chinese-claimed territory.
"We go wherever international law enables us to go," he told reporters in Canberra.
China claims virtually all of the South China Sea, inflaming regional tensions when it started building its own islands on disputed reefs, adding airstrips, radar and communications and defence systems, plus troops.
It insists the 12 nautical mile territorial limit applies.
The US, Australia and other nations cite international law which says the 12 nautical mile rule doesn't apply for artificial islands.
Vice Adml Johnston said RAAF aircraft had been engaged in what's called Operation Gateway since 1980, conducting patrols of the Indian Ocean and South China Sea.
That happens around four to eight times a year, with daily flights for up to a fortnight. During these missions, aircraft operate from the Butterworth air base in Malaysia.
Vice Adml Johnston said Chinese ships had challenged RAAF aircraft previously so what happened last month wasn't unique.
Prime Minister Malcolm Turnbull won't flag future Australian Defence Force activities in this area.
"We are absolutely committed to freedom of navigation and freedom of overflight in accordance with international law, as indeed is Japan," he told reporters in Japan.
Australia took no position on territorial claims in the region, insisting they should be settled peacefully whatever their merits.
"All actors should aim to ensure that whatever they do does not exacerbate tensions and/or raise the risk of conflict," Mr Turnbull said.