Will NATO Walk the Walk?

Slap this guy down or look like wussies. Those are NATO's options as its commanders issue an urgent warning to President Slobodan Milosevic in Belgrade on Tuesday. The Serb leader has already made clear his contempt for NATO's threats by expelling the U.S. head of an observer mission following last week's massacre of 45 ethnic Albanians. "Europe is outraged, and the climate for military action is a lot stronger than it was over Iraq," says TIME U.N. correspondent William Dowell. "And unlike Iraq, where there was no clear target, the Serb armor and artillery in Kosovo are vulnerable to air attack."

Besides the presence of 700 Western observers and opposition from Russia, NATO's prime concern may be to avoid taking sides in a war where they support neither combatant. "NATO doesn't want to be the air force of the KLA rebels," says Dowell. "But the Serbs have thrown down the gauntlet, and failing to respond would make NATO look impotent."