The 9/11 terrorist attacks were carried out by 19 hijackers affiliated with the Islamist extremist group al-Qaeda. This organization was founded and led by Osama bin Laden, who orchestrated the attacks. The hijackers took control of four commercial airplanes on the morning of September 11, 2001, flying two into the Twin Towers of the World Trade Center in New York City, one into the Pentagon in Arlington, Virginia, and crashing the fourth in Pennsylvania after passengers intervened
. The key planner behind the attacks was Khalid Sheikh Mohammed, who proposed the idea of using hijacked planes as weapons. He coordinated closely with bin Laden, who provided the resources and strategic framework for the operation. The hijackers were mostly from Saudi Arabia and had received flight training in the United States
. Following the attacks, U.S. intelligence and law enforcement agencies quickly identified al-Qaeda and Osama bin Laden as responsible. Bin Laden initially denied involvement but later publicly claimed responsibility in 2004. The attacks led to a global manhunt for bin Laden, who was killed by U.S. forces in Pakistan in 2011
. In summary, the 9/11 attacks were planned and executed by al-Qaeda under the leadership of Osama bin Laden, with Khalid Sheikh Mohammed as the chief operational planner
