S. military and Iraqi civilian deaths and Americans commanders say they know why: the U.S. troop increase and an Iraqi groundswell against al-Qaida and Shiite militia extremists.

• 美军指挥官说他们知道原因所在：美军驻军的增加和伊拉克人民迅速增长的对基地组织和什叶派极端主义民兵的自发狙击。