"The record is stunningly clear. Air forces cannot get at an opponent on the ground unless accompanying troops force [the opponent] to concentrate in a particular area," Van Evera said.

Nash said he would support a ground war, but thought it presented "strategic and operational limitations" because of previous declarations that we would not consider such an option.

"It could take two months to put ground forces in place, with a plan of action," he said.

While other panelists said an initial buildup of ground forces might have led to a less inflamed crisis, perhaps even making Milosevic capitulate on his own under the threat of so much force, Nash had a mild demurral.

"Don't assume that if we had done one thing, everything would have been OK. During the buildup of a NATO ground force, what would Serbs have done given [the atrocities they committed] during the air attack," Nash said.

Jennifer Leaning, assistant professor of medicine at Harvard Medical School and a board member of the group Physicians for Human Rights, denied that NATO was at fault for escalating the human rights crisis in Kosovo. She argued instead that Milosevic was determined to eliminate the Albanian population of Kosovo from the start.

"What Milosevic was doing was patently clear...it was evident to us in October that Milosevic was intent on wiping out that population and that war was necessary," Leaning said.