President Bush's promise to defend Taiwan against Chinese attack sent America's China-hand aristocracy into coughing fits last week. "The language on Taiwan is very arcane, very nuanced," said former ambassador Winston Lord, "and people are apt to make mistakes with it." Indeed. But what really frightens the China hands is the possibility that Bush's statement was less a mistake than blunt talk straight from the president's gut.

The truth is, the "One China" policy has been slowly but steadily collapsing under the weight of its own contradictions for more than a decade. And how could it not collapse? America's very arcane, very nuanced policy was created in 1979. The world then was so different from today's that it might as well have been 1879. In 1979 the Soviet Empire looked like an insatiable and unbeatable monster. China seemed to be a genuine strategic ally. Taiwan was a creepy dictatorship, clutching tired old visions of reconquering the mainland.

To American diplomats eager for a total Sino-American embrace and partnership against Moscow, Taiwan was just an annoying little obstacle to the unfolding of their grand strategic schema. Taiwan had to be brought in line with American designs. Before 1979 China had been deterred from attacking Taiwan by a mutual defense pact between the United States and the island. But after 1979 it was the Taiwanese who needed to be made insecure.

Hence the birth of America's "strategic ambiguity" with its unmistakable message to Taiwan's leaders: Act up, provoke the Chinese, refuse to play ball and the United States just might let you fry. For the next two decades, strategic ambiguity and the policy of limiting arms sales to Taiwan had one purpose: to keep the Taiwanese in a constant state of fear. Fear of Chinese attack would deter them from declaring independence. Fear of American abandonment would make them pliable in negotiations with the mainland. Strategic ambiguity was the key pillar of the new Sino-American relationship, for without it Beijing would correctly view America's "One China" policy as hooey.

A decade after this policy was put in place, however, the whole world turned upside down. In 1989 the Soviet Empire collapsed. With the disappearance of the Soviet threat went America's interest in a strategic alliance with China. After Tiananmen Square, China appeared as a particularly odious regime and began to emerge as a potential strategic adversary.

Taiwan meanwhile was evolving into an exemplary democracy, and in the process the Taiwanese people lost all interest in returning to the mainland, much less uniting with it. By the early 1990s there were, quite clearly, two Chinas. And the United States no longer had a compelling strategic interest in insisting that there should be only one.

Faced with this global strategic and ideological revolution, the China policy priesthood clung like medieval monks to their old catechism. They insisted that although China, Taiwan and America's moral and strategic imperatives had all changed, American policy must not change. Each new president in the post-Soviet, post-Tiananmen era had to be trained in the old mysteries, to perform the rituals and intone the mystical words of their ancestors: "There is only one China."

But secretly the priesthood worried. In this new world, how long would the American people support a policy that deliberately held the threat of annihilation over a democratic friend in the interest of coercing its reunification with an authoritarian adversary? How long before American military planners began doubting the strategic wisdom of giving a militaristic Beijing and nervous Asian allies the impression that the United States might let Taiwan be bullied and perhaps overrun? And how long before some plain-spoken guy in the White House, when asked if he would defend Taiwan against a Chinese attack, suddenly forgot or ignored the priesthood's talking points and instinctively, common-sensically responded, "Yes. Whatever it takes"?

So now the moment the China hands dreaded has arrived. The newspapers overflow with the nervous cluck-clucking of Sinologists puzzled and dismayed by the uncharacteristic frankness of an American president. The priesthood has scrambled to "walk the cat back," to try to inject some ambiguity into Bush's unambiguous rejection of strategic ambiguity. And Bush, fearing he made a mistake, dutifully has suppressed his common-sense instincts and performed the old sacred rituals, declaring robotically that he still supports the "One China" policy, opposes Taiwan's independence and abides by the deliberately vague and ambiguous "commitment" of the Taiwan Relations Act.

But the fact is, it's over. Strategic ambiguity was on its deathbed after the Clinton administration sent two aircraft carriers to defend Taiwan against Chinese missile rattling in 1996. Clinton tried to revive it by promising Beijing the moon, but on Wednesday Bush killed it. With the destruction of this pillar, the "One China" policy is falling to the ground.

The Chinese government, disabused of its decades-old hope that the United States would help deliver Taiwan to the altar of reunification, likely will increase its already prodigious efforts to achieve that goal by force. The Bush administration, in turn, will have to redouble its efforts to deter all plausible means of Chinese attack. No matter how often Bush repeats the "One China" mantra, as a practical matter American policy will be based on the principle of two Chinas, not one. And before too long, as the pressures of this confrontation grow, other revered China policy shibboleths will begin to topple, such as the myth that the United States can engage the Beijing oligarchs as an economic friend while it confronts them as a military adversary.

The old China hands and their allies in corporate America are furious at President Bush for bringing us to this point. The rest of us can thank him. With a few words Bush has dragged the United States across the threshold from the era of illusions into the era of reality. That can never be a bad thing. And it was not a mistake.