The 30-year-old policy of "strategic ambiguity" on Taiwan, the most sensitive issue in Chinese-American relations, has become a little less ambiguous with President Bush's warning to Taiwan not to take any unilateral action toward independence.
In a series of agreements dating back to the US-Chinese Shanghai Communiqué of 1972, the United States acknowledged that "there is but one China and Taiwan is part of China."
The US has implied since then that it would come to Taiwan's defense if the island were attacked, but not if Taiwan tried to assert its own sovereignty.
That formula has basically held all these years while trade with China boomed and President Clinton spoke of a "strategic partner." Mr. Bush, in his campaign for president, changed that to "strategic competitor." But the relationship held through strains over Chinese human rights policy and the midair collision with an American spy plane.
As time passed, the Bush administration began to perceive new needs for China's goodwill - currency revaluation to aid American exports, cooperation in the war on terrorism, and brokering North Korea's dismantling of its nuclear program.
And so, when Taiwan's President Chen Shui-bian, attentive to his own electoral needs, proposed holding a referendum that hinted at a campaign for independence, the Bush administration took vigorous exception. In the presence of visiting Chinese Premier Wen Jiabao, the president warned Taiwan against "any unilateral decision ... to change the status quo."
Mr. Chen has continued talking about holding a "defensive referendum" demanding withdrawal of Chinese missiles aimed at Taiwan, but he stresses that he is not talking of a vote on independence. The government in Beijing has praised Bush for standing up to Taiwan.
Bush's stern warning to Taiwan may not accord with his mission of spreading democracy around the world, and it may not go down well with his conservative base. But the president has clearly made a pragmatic decision that the US has too much at stake in China to allow Taiwan to disturb the tacit truce that has served for three decades.
• Daniel Schorr is a senior news analyst at National Public Radio.