After the United States was attacked by terrorists on September 11, 2001, its European allies were among the first nations to express sympathy and pledge their aid in the war to come. The fact that many European countries have long experienced terrorism themselves helped ensure a great deal of transatlantic empathy and cooperation- at least at first. France, Germany, Italy, Spain, and the United Kingdom have suffered political violence over the past 30 years and were thus predisposed to help the United States its new struggle against al-Qaeda. But the kind of terrorism these European countries have suffered-"old" terrorism-differs substantially from that suddenly faced by the United States. As time passed, these differences started to erode the through going unity that had flourished right after September 11.