Sheik Kamal Maamouri, the leader of one of the largest Shiite-dominated tribes in Iraq, used to call the United States troops here occupiers, demanding that they withdraw because he said they killed and imprisoned innocent members of his tribe. But now he is not so sure he wants the Americans to go, at least not yet. Like many others across Iraq, he felt conflicted, and a bit frightened, after it was revealed last week that the United States may keep 3,000 to 4,000 troops in Iraq next year. “The political changes that have occurred here and the security problems have...