initiatives to combat terrorism and defined the presidency of George W. Almost 3,000 people were killed during the 9/11 terrorist attacks, which triggered major U.S. Two of the planes were flown into the twin towers of the World Trade Center in New York City, a third plane hit the Pentagon in Arlington, Virginia, just outside Washington, D.C., and the fourth plane crashed in a field in Shanksville, Pennsylvania. On September 11, 2001, 19 militants associated with the Islamic extremist group al Qaeda hijacked four airplanes and carried out suicide attacks against targets in the United States.
