The Definition of Terrorism Terrorism is a term that has no universal definition, and the challenge arises when determining the basis of deciding when the use of violence is valid. Some definitions put forward are either too specific or too indistinct where concentration is on some essential "t...

In the early morning hours of September 11, 2001, hijackers from the terrorist group al-Qaeda took control of four United States airplanes. Two of them brought down the Twin Towers in New York City. One of them severely damaged the Pentagon building in Washington D.C. The fourth plane crashed int...