In the aftermath of the terrorist attack on September 11, one question has been on everyone's mind: "How did this happen?" This book seeks to answer this question in all its critical aspects -- the motives and actions of the terrorists, the status of the U.S. military, the context of the Middle East, bioterrorism, airport security, diplomatic pressures -- and to provide readers with perspective, information, and sound interpretation. The editors of Foreign Affairs have brought together noted experts whose insights make the events of that terrible day more understandable, even as we steel ourselves for the conflicts ahead.