Expectations are building that the United States will soon send navy patrols close to the artificial islands China has constructed in the South China Sea, pushing back against China's pursuit of regional power. It is an exercise in brinkmanship that must be carefully calibrated. The risky manoeuvre could come as early as next week. 
China has already signalled its displeasure as Australian and US defence and foreign ministers jointly reiterated their commitment in Boston this week to the "freedom to navigate", accusing them of "adding fuel to the flames" of an already-tense situation.
According to US media reports, US officials have briefed Asian allies on plans to patrol within the 12-nautical-mile zone around at least one of the islands, which China has built on rocks and reefs in the past two years to bolster its claims to sovereignty over a large swath of the sea, the world's busiest shipping route.
A backdown now seems unlikely as it would seriously undermine American regional prestige. Yet the exercise will only confirm China's view that the US prime foreign policy objective towards it is to derail its date with destiny as a rich and powerful nation. It has real grievances with some of the latest developments in its neighbourhood: the Trans-Pacific Partnership has left it out in the cold, while the change to Japan's pacifist constitution rankles deeply with a nation that suffered so extensively from Japanese aggression. US lectures about abiding by international rules ring hollow to Chinese ears in the light of George Bush's adventurism in Iraq.
While a US patrol into the area is unlikely to be met with missiles on the orders of Beijing, there is an immediate risk of accidental collision or rogue weapons being fired, provoking further conflict.
More certain is Chinese retaliation in some other way, perhaps along the lines of its attempt to put an oil rig within Vietnam's exclusive economic zone. China may well argue the US actions justify a reversal of Xi Jinping's pledge in Washington not to militarise the islands.
US patrols will not be the end of the game of bluff in the South China Sea, and it is a game fraught with the danger of escalation.
So why play at all? In particular, why should Australia voice such full-throated support for America's position on the issue? Former foreign minister Gareth Evans argues China should be believed when it says it is not in the business of disrupting commercial shipping or flights. This strikes us as too sanguine. China has form using economic weapons. It stopped rare-earth shipments to Japan and imposed import restrictions on Philippine bananas over territorial disputes.
The protection of the maritime commons is a worthy aim. But it would be best if the US could mount its patrol jointly with Asian allies that also have claims in the sea. This would take some of the colonialist sting out of it. Trade Minister Andrew Robb said Australia would not join any patrol, and it should not without this broader coalition in place. Above all, the US must not let conflict reach a point where it interferes with opportunities to work with China, such as at climate negotiations in Paris. Such trust-building exercises promise a better future than gunboat diplomacy.