PENTTBOM
PENTTBOM (sometimes spelled as PENTTBOMB) 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 (1 and 2 World Trade Center) in New York City.