"To me that's a continuation of the war," Edwards said. "Combat missions mean that the war is continuing. I believe the war needs to be brought to an end."
Edwards' broadside put Clinton on the defensive at a time when she is enjoying a comfortable lead in opinion polls and trying to appear above the fray. But there was no sign that the debate would prompt a major shake-up in the Democratic field.
"There may be a continuing counter-terrorism mission," she said, while adding that "the vast majority" of American troops would be out of Iraq by the end of her prospective first term in 2013.
The cross-fire on the campus of Dartmouth College came at the first debate of the critical autumn season leading up to the early voting contests in January ahead of the November 2008 election to replace President George W. Bush.
Iraq was a dominant theme of the debate as Democrats seek a way to force Bush to change his war strategy, which may leave as many as 100,000 troops there by the time the next president is inaugurated in January 2009.