PENTTBOM

Summary

PENTTBOM was the FBI's investigation into the terrorist attacks against the United States on September 11, 2001 (9/11), in which 19 members of al-Qaeda hijacked four U.S. commercial airliners in an attempt to crash them into national landmarks. The name is short for "Pentagon/Twin Towers Bombs", the "bombs" being three planes that had hit the Pentagon in Virginia, and the Twin Towers in New York City. The fourth plane crashed in Pennsylvania following passenger intervention.