Pentagon planners warn that U.S. aviators flying for NATO are likely to suffer casualties from the Serbs' sophisticated air defenses, and there is no apparent end-game strategy for terminating the military assault.
It's only been in the past few days that Mr. Clinton has tried to explain to the American public why it should care about what's happening between Kosovo - a Yugoslavian province the size of Maine - and the government of Yugoslav President Slobodan Milosevic in Belgrade.
To the Serbs, this is out of the question. They regard Kosovo as the center of their history and tradition. More practically, Milosevic fears losing still another piece of territory from the now much-shrunken Yugoslavia.
So, the Yugoslav Army has been battling a guerrilla force from Kosovo which calls itself the KLA, or Kosovo Liberation Army. Despite a cease-fire last October, the fighting has continued, often accompanied by gruesome mass murders the Serbs call "ethnic cleansing."
At last Friday's news conference, Mr. Clinton said that he believed Milosevic had already crossed the threshold, but nonetheless he sent special envoy Richard Holbrooke back to Belgrade in a last-minute attempt to get Milosevic to back down.
On Tuesday morning, as Holbrooke departed Belgrade with no progress to report, the president met with members of Congress. Some had opposed U.S. participation in the NATO mission, but most left the meeting saying they would support the troops, even if not the administration's policy.
Then Mr. Clinton resumed the task of explaining this to the public. Before a union audience, the president called this a question of values. "What if someone had listened to Winston Churchill and stood up to Adolf Hitler earlier?" he asked. "How many people's lives would have been saved?"
What we learned in Bosnia, said Mr. Clinton, is that "If you don't stand up to killing, they'll do more of it." And later: "If President Milosevi is not willing to make peace, we are willing to limit his ability to make war on the Kosovars . . . it is morally right and in the vital interests of the United States."
What's more, he argued, there's a practical reason to act as well as a moral reason.
"If we don't do it now, we'll have to do it later. People will die and it will cost more money," he said.
One critic on Capitol Hill called this the speech the president should have given weeks or months ago to make the case that military action in which the nation will sacrifice blood and treasure is necessary.
Vietnam remains the classic example of the futility of waging war when the American public doesn't understand or believe in what the government is doing. Recall how carefully George Bush prepared the nation for the Gulf War.
If this attack goes forward with the kind of surgical precision which has characterized the continuing air strikes on Iraq, the president will have no problem.
But if Americans die, or are captured and humiliated, it is Bill Clinton who is likely to be blamed - unless the nation comes to believe that Slobodan Milosevic must be stopped.
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