Among the most significant characteristics of the September 11 attacks were the ambitious scope and dimensions of the operation; its coordination; and the unswerving commitment of the 19 aircraft hijackers in preparing for and executing the attacks that killed 3,000 persons, the aircraft passengers and crews, and themselves. The failure of U.S. authorities to predict or envision the possibility of the September 11 scenario involved a limited view of terrorist capabilities, a failure to consider the various means by which terrorists could achieve mass casualties, a failure to see the clues from previous terrorist efforts to use airplanes as weapons, and the United States' lack of political will to sustain a long and demanding counterterrorism campaign. U.S. intelligence also failed to understand and appreciate Usama bin Laden and his cohorts in terms of their vision, capabilities, financial resources, and organizational skills. The September 11 attacks should tell U.S. authorities that the terrorists affiliated with al Qaeda have a single-minded determination to find ever more effective ways to kill Americans and/or disrupt the American way of life. Future attacks may focus on computerized electronic networks that are the heart of financial, business, transportation, and governmental operations. Terrorists will continue to be enamored with weapons that kill and invoke terror in civilian populations. These may include low-level biological and chemical agents distributed in such a manner as to terrify the masses. Terrorism will persist and the struggle against it requires constant vigilance and the commitment of resources to sophisticated and widespread intelligence activities and countermeasures that are tireless, innovative, and dynamic. 33 notes