Terrorism has been in existence for a long time, yet the experts are still finding difficulty defining exactly what it is. Terrorism has been defined as : "Premeditated, politically motivated violence perpetrated against noncombatant targets by sub national groups or clandestine agents, usually intended to influence an audience." However it is defined, there is agreement that there are certain elements that much be present for an act to be classified as terrorism. Some experts agree that it must be politically motivated and that the targets must be random. It is thought that the intention is to make everyone afraid of being a target. The CIA's Counter terrorist Center adds that it must be premeditated and not just an impulsive act, and aimed at civilians. Terrorist acts can be considered barbaric because of the extent of the damage that is inflicted, and so it is difficult to understand why anyone would be motivated to carry out such an act. In past history there have been many reasons for such terrorist acts such as to produce fear, to harass weaken or embarrass a government security forces, to satisfy vengeance, to steal money and equipment especially weapons, to free prisoners, and to obtain worldwide or local recognition for a cause. In order to be effective on a large scale the common method of terrorism is by bombing. Perhaps the most remembered in recent history is what is now known simply as 9-11. This was an unusual mode of terrorism where planes were simultaneously flown into public buildings in crowded cities. The deadliest was at the World Trade Center in New York city where more than 3,000 lives were lost. But that was not the first time that the World trade Center was the target of terrorism. In February 1993, a truck bomb exploded there, killing six people, and displacing business in the complex for six months. Terrorists acts are not always carried out by groups.