9/11 Terrorist Attacks

The 9/11 terrorist attacks occurred on September 11, 2001, when 19 terrorists from the extremist group al-Qaeda hijacked four commercial airplanes. Two planes crashed into New York City's World Trade Center towers, causing their collapse, while a third hit the Pentagon and a fourth, United Flight 93, was taken over by passengers and crashed in Pennsylvania. Nearly 3,000 people died, marking the deadliest terrorist act in U.S. history. The attacks led to significant changes in U.S. foreign and domestic policies, including the War on Terror, increased security measures, and the invasion of Afghanistan to dismantle al-Qaeda's operations.