Clearly stung by the criticism that the air attack has only made things worse for the Kosovar Albanians, the Clinton administration insists that Milosevic would have attacked Kosovo in any event.
A senior official called attention to Milosevic's similar campaign in Bosnia, where two million people were displaced and 250,000 died.
"If we hadn't done anything this time," the official told CBS News, "you'd still be seeing the ethnic cleansing that's going on now - and NATO would be in Brussels with its finger up its ear."
White House officials say the NATO offensive can end in one of two ways. Milosevic can agree to the peace plan worked out in talks at Rambouillet, outside Paris. That deal calls for an end to the fighting and for an international security force to be placed in Kosovo.
Or the U.S. and NATO can decide that they have met their military objectives and sufficiently diminished Milosevic's capacity to make war.
The administration argument is that the only rational way for Milosevic to keep Kosovo from becoming independent is to agree to the peace accords and the international force. But to Milosevic, rational behavior may have more to do with exercising his power and catering to the nationalism of his Serb population.
And the longer the NATO campaign - and Milosevic's ethnic cleansing - continue, the more the question arises: won't it take ground troops to end this?
The answer from the White House: It's not a question of sending in the troops or watching the slaughter of civilians.
A senior official told us, "I don't believe it's in our interest or NATO's to launch a land attack on Serbia in order to defeat and occupy it for an indefinite period of time. I'd hate to be on the Hill answering questions about that. I don't think we can justify the cost."
What about the possibility that no one wins? What if NATO decides its military objectives have been met and stops bombing, but Milosevic still hasn't agreed to peace terms? This outcome, which becomes more likely as this offensive continues, would mean a continuing civil war in Kosovo - although one in which the balance of power might favor the Kosovars.
For all the theorizing, it's quite clear that Milosevic has ignored NATO's air power for longer than the planners believed he would. And it's clear that there's no well-defined endgame - or at least none which doesn't leave the situation almost as unstable as when it began.
It's also clear that this is not an easy call. The U.S. may not - or should not - be able to intervene every time and everywhere a despot raises his head. But tell that to the Kosovar Albanians who are urging NATO to keep up the ombing even as they are burned out of their homes and chased by squads of executioners.