This article analyzes NATO’s decisions and actions taken in response to the 11 September 2001 terrorist attacks against the United States and assesses the probable future role of the Alliance in combating international terrorism. In September-October 2001, the United States chose to lead a coalition against the Al Qaeda terrorists and their supporters in Afghanistan instead of ceding the initiative to NATO. The necessity for rapid decisions and actions, the military capabilities gap between the United States and the European allies, and the lessons from NATO’s air campaign in the 1999 Kosovo crisis, probably led the United States to make this choice. NATO’s contributions to the campaign against terrorism have included sending Airborne Warning and Control Systems aircraft to the United States, deploying naval forces to the Eastern Mediterranean, and conducting preventive action against terrorist groups acting within or from the Balkans. Other measures taken by the Alliance include: adoption of a new Military Concept for Defence against Terrorism and a Partnership Action Plan on Terrorism, strengthening the nuclear, biological and chemical defence and civil protection, better cooperation with other international organizations, etc. NATO’s responses to the 11 September attacks, the unconventional and asymmetric threat posed by international terrorism, and the distinct contributions that the military can make in combating terrorism support the main hypothesis of this article: that NATO may be unable to play more than specific limited roles in the fight against international terrorism.