"We urge the relevant sides to stop applying [a] double standard. It would be more helpful if they would honour their commitment of not taking sides on relevant disputes and do more to promote regional peace and security...rather than light a fire and add fuel to the flames," the embassy spokesman said.

Anticipation is growing that US warships will soon sail within 12 nautical miles of disputed reefs in the Spratly archipelago that China has defiantly built on in the face of competing territorial claims from The Philippines, Malaysia and Vietnam.

"Now, make no mistake", Mr Carter said, "The United States will fly, sail, and operate wherever international law allows, as we do around the world, and the South China Sea is not and will not be an exception."

Canberra is supportive of Washington's mooted "freedom of navigation" exercise to test China, but the naval cooperation announced at the Australia-United States Ministerial consultation does not extend to local ships or naval bases being used to launch such a mission.

The port of Darwin is thousands of kilometres from the hotspot and the US is more likely to begin any mission from Japan or other closer Asian allies.

Instead, the naval agreement largely reiterates plans to ramp up joint training and exercises, with precise details absent at time of the announcement and subject to further discussions between officials.

Australian naval boats already operate independently through the South China Sea as a matter of course and will continue to do so.

Amid tension over Beijing's belligerence, Australia and the US are trumpeting a surprise public statement by President Xi Jinping at the White House last month that China would refrain from militarisation of the artificial islands.


An official said Mr Xi's announcement was a shock because he had not mentioned it in his earlier private conversation with President Obama.

"We welcome President Xi's statement that they do not intend to militarise the Spratly Islands and we will certainly take some comfort in that and hold them to that statement," Ms Bishop said.

Beijing has previously constructed airstrips and buildings capable of hosting military personnel and hardware on the artificial islands.

Senator Payne, who was sworn in as Defence Minister last month, said she was committed to the "full implementation of the US force posture initiatives", including increasing the American marines rotating through Darwin to 2500, up from 1150 currently.

The defence minister and Mr Carter signed a joint statement on defence co-operation, including enhancing the interoperability of their military forces, intelligence co-operation and building co-operation with regional partners.

In the battle against Islamic State, which has been complicated by Russia's sudden insurgence to prop up the regime of Syrian dictator Bashar al-Assad, Australia pressed the US for assurances on the safety of its pilots deployed there.

The US is close to signing an agreement with Moscow on protocols intended to avoid inadvertent in-air clashes between Kremlin and coalition jets.

In Afghanistan, the US will soon make a formal request for Australia to extend the stay of up to 250 troops due to exit the war-torn Middle East country in 2016.

"I assured Minister Payne that the United States is absolutely committed to seeing the mission through beyond 2016," Mr Carter said.