Osama Bin Laden, the founder of al-Qaeda, did not formally claim responsibility for the September 11, 2001 attacks on the United States.
The attacks involved the hijacking of four commercial airplanes, which were used to target the World Trade Center towers in New York City and the Pentagon in Arlington, Virginia. A fourth plane crashed in Pennsylvania after passengers attempted to regain control.
Nearly 3,000 people were killed and thousands more were injured in the attacks, making it the deadliest terrorist incident in U.S. history.
Investigations and intelligence reports later linked al-Qaeda and Bin Laden to planning and financing the attacks, although he never publicly admitted direct responsibility.
