SPLIT, Croatia -- On June 28, 1914, a Serbian nationalist named Gavrilo Princip assassinated the heir to the Austro-Hungarian throne in Sarajevo, so igniting World War I.
For three years after that, Woodrow Wilson stayed out of the war, arguing that the United States should remain neutral in order to mediate between the belligerent European powers.
It is now three years since another, smaller European war began in Sarajevo, and two U.S. presidents, George Bush and Bill Clinton, opted to wait and watch, leaving the initiative to European allies whose instincts for peacemaking have proved unequal to the calamity.
Last week, the Clinton administration came closer than ever to direct involvement, providing the political will and the bulk of the aircraft for the most punishing NATO air strikes yet on the Bosnian Serbs.
Intense U.S. lobbying of European allies led to the bombing of an area close to the Bosnian Serb headquarters in Pale.
The initial result of the U.S.-backed effort was, however, disastrous. And the apparent debacle seemed to bring closer the day when U.S. troops may be asked to go to Bosnia and help pull out all or most of the 22,000 United Nations peacekeepers.
Such a deployment in Bosnia is one of the things the United States wanted to avoid by encouraging the United Nations and NATO to get tough at last with separatist Serbs.
But the policy may have backfired. France, the largest contributor to the peacekeeping force, has now had about enough.
The disaster was scarcely hard to foresee. The Serbs, as they have after milder NATO strikes, took hundreds of U.N. soldiers hostage, this time using some as human shields. Then they killed two French peacekeepers in fire fights.
They also fired the deadliest single shell of the war, killing 71 people in the northeastern town of Tuzla -- a massacre more bloody than at the Sarajevo marketplace last year.
They shelled other mainly Muslim towns, killing and maiming civilians. Unconvinced that NATO would press on with its assault (a reasonable assumption in the circumstances), the Serbs ignored a U.N. ultimatum to hand over guns that are again subjecting Sarajevo to terror.
All this underscored a point that became evident a long time ago in Bosnia: U.N. relief missions and the use of NATO force as an instrument of foreign policy do not go together.
In that humanitarian efforts aim to make crises more endurable, while military force aims to resolve them, they are essentially incompatible.
The Europeans, whose soldiers are on the ground, have been able to disregard this truism by resisting, until now, the U.S. urge to mount the kind of raids that might impress the Serbs. And the United States could disregard the truism by declining to contribute peacekeepers to share the risk of direct reprisal.
Even recently, Gen. John Shalikashvili, the chairman of the Joint Chiefs of Staff, said of Bosnia: "I believe that whenever we have been resolute -- NATO particularly -- we have been able to have our way."
A lack of resolution -- except over the need to avoid putting U.S. soldiers in Bosnia -- has, however, been another hallmark of the Bush and Clinton administrations' Bosnian policies. This is a problem partly traceable to European reluctance to agree to strong action; still, U.S. pronouncements have made it transparent.
Now, however, a fork in the road appears to have been reached because it is clear that being "resolute" from the air while U.N. peacekeepers remain on the ground produces little that is good.
So if France and Britain one day need help in withdrawing their peacekeepers, Americans will have to measure their reluctance to put GIs in harm's way against the harm that a refusal would do to their most important friendships.