A big question facing every US president since the Vietnam War is the likely hesitancy of Americans to see their troops put at risk in a conflict.
In a test of US resolve, China's powerful military held 24 American crew members for more than 11 days, hoping to extract such concessions as a kowtowing apology and a promise to end surveillance flights near Chinese shores.
It badly miscalculated. The only life lost was the hot-dogging Chinese fighter pilot who flew too close to the US plane.
Quiet and stern diplomacy to free the aircrew, the US made its point about defending its vital interests in Asia.
One of those vital interests is Taiwan, a nation that has proved Chinese people really can run a healthy democracy. But the US has no formal commitment to defend Taiwan. And China expects it will need to take the island by force someday.
So this latest incident, in the eyes of China's military, was shadow play for an eventual conflict over Taiwan - one that a weaker Chinese military could win only by eroding US resolve to fight, the same way North Vietnam did in the 1960s.
Chinese leaders have surely looked at US opinion polls such as one by the Chicago Council on Foreign Relations that shows little American will to defend Taiwan (27 percent).
They are probably also aware that President Bush's foreign-policy chiefs differ on when to deploy US troops and in their tolerance for casualties. Secretary of State Colin Powell, for instance, has a history - born of his time in Vietnam - of not backing many recent instances of US involvement, as in Haiti. He generally does not believe force should be threatened or used as a tool of diplomacy.
China may have believed that the "Powell doctrine" would restrict US military options. But Mr. Bush put Mr. Powell in charge of ending this standoff with China, and the secretary of State showed that nuanced statements - such as avoiding the word "hostages" to refer to the detained aircrew - and keeping US opinion behind the administration can lead to success.
Will China now get the message that the US isn't a pushover? It didn't after a similar incident with the US in 1996. Let's hope it did this time.
(c) Copyright 2001. The Christian Science Monitor