There comes a time in every poker game when you have to decide whether the other guy is bluffing, or whether he really does hold a stronger hand than you do. If he does, it's time to stop raising the stakes because from that moment on, you are only increasing your losses. Instead, you should say goodbye to your bet and bow out gracefully, hoping for a chance to play again another time, with better cards.
The news last week that China has deployed advanced, long-range surface to air missiles (SAMs) to Woody Island in the disputed Paracels marks the point at which US policymakers need to make this call about their game with China in the South China Sea. They ought to be asking themselves how sure they should now be that American diplomatic pressure, backed by low-risk symbolic military manoeuvres, will force China to back off from the provocative assertion of its claims over contested features and waters in the South China Sea.
That is not because the newly deployed missiles radically change the military balance in the region. China has long sent fighter aircraft to the same base on Woody Island, so its capacity to defend the airspace it claims is not entirely new. Nonetheless, the HQ-9 is a very potent weapon. It is an impressive example of how quickly and successfully China has been able to develop and improve the systems and technologies it had acquired from the former Soviet Union and elsewhere to produce advanced air and naval capabilities that are now comparable with any in the world.
And like any capable long-range SAM, the HQ-9 poses tactical challenges to any adversary operating within its wide combat radius which are different and in some ways more formidable than those posed by fighter aircraft. The missiles' presence would therefore certainly affect tactical calculations, and limit the operational options, of any other air force flying in their vicinity.
However, the real significance of these missiles' deployment is the strategic message it sends about China's resolve, and its confidence in having the upper hand against America in the South China Sea. This undermines the entire logic that has driven US policy on the South China Sea ever since this time last year.
That policy aims to use the South China Sea issue to reassert US strategic leadership in Asia against China's growing challenge by raising the diplomatic and military temperature over the issues there - especially China's developing island bases - to the point that Beijing blinks and backs off. That's what we've seen ever since the US Pacific Commander started talking about Beijing's newly-built island bases as its "Great Wall of Sand" last April.
The stakes for China's leaders are very high, because today's dispute in the South China Sea is not about rocks and reefs, or about the Law of the Sea. It's about whether China must continue to acknowledge US leadership in Asia, or can take America's place as Asia's primary power - as policymakers in Washington are only now starting to understand.
But, of course, this policy assumes that China will indeed blink and back off. It presupposes that America can impose diplomatic costs and military risks on Beijing that are high enough to make its leaders abandon their pushy posture in the South China Sea. And it presupposes that America can impose those costs and risks on Beijing at a price that it is willing to pay itself. So it works only if China's tolerance for diplomatic embarrassment and military risk is lower than America's.
But what has become clearer since April last year, and has now been underlined decisively by the SAM batteries on Woody Island, is that that this is not the case - especially in regard to the dangers of a military confrontation. Washington has been energetically trying to raise the diplomatic costs to Beijing by courting South-east Asian partners - as US President Barack Obama did last week at the Sunnylands summit with Asean leaders.
But it has been much more timid on the military front. After a lot of tough talk about sending its navy and air force wherever international law allows, Washington has been very reluctant to approve freedom of navigation operations to defy China's maritime claims, and those that have occurred so far were carefully scripted to minimise any serious challenge to Beijing and not offer a pretext for a robust Chinese military response.
Evidently, policymakers in Washington are not willing to run even a small risk of a military confrontation with People's Liberation Army forces, fearing that it might escalate into a clash which would prove impossible to contain.
Beijing, on the other hand, has not blinked. In response to US actions, it has taken steps that signal plainly its willingness to risk a confrontation rather than step back from its positions in the South China Sea. This is what China has done more starkly than ever with the recent SAM deployment, which is why it is time for America to rethink its strategy.
Some people in Washington and elsewhere - like the old warhorse Senator John McCain - say that the US now has no choice but to take some risks because the only possible response to China's move is to push back harder. Anything less would be surrender, so they urge more, and more intrusive, US military operations around China's claims, perhaps in conjunction with US allies and partners like Japan and Australia. But they need to think very carefully how China would respond in turn. Is there any reason to believe that Beijing would not simply push back harder yet again, perhaps by sending SAMs to the Spratlys, or declaring an air defence identification zone? And what would the US do then? How many rungs up the escalation ladder is it willing to climb?
And the risk of China responding with yet another counter- escalation is high, for two reasons. The first is that they have grown confident that America would eventually back off to avoid a confrontation, so they don't have to. The second is that the stakes for China's leaders are very high, because today's dispute in the South China Sea is not about rocks and reefs, or about the Law of the Sea. It's about whether China must continue to acknowledge US leadership in Asia, or can take America's place as Asia's primary power - as policymakers in Washington are only now starting to understand.
And that poses the big question for Washington: Is America more determined to preserve US regional leadership than China is to take its place? Which of them is ultimately more willing to risk a clash to achieve their aim? Because whichever is more determined, and can convince the other of that, will win this game of bluff. And so far China is winning.
That means America needs to be very careful about what it does next. But China needs to be careful too. America is a proud country, and it can be a dangerous and unpredictable adversary. It would be unwise to be too sure that America will keep backing off to avoid a confrontation - even if that would be contrary to America's deepest interests. It might be a massive mistake for America to risk war with China over the leadership of Asia, but that would be no consolation to China if it finds itself locked into such a war anyway, because the costs to China too would be incalculable. One hopes the hard men in Zhongnanhai know that sometimes the most dangerous moment is when you seem to be winning.
The writer is professor of strategic studies at the Australian National University in Canberra.
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