On September 11, 2001, a series of coordinated terrorist attacks were carried out by the extremist group al-Qaeda in the United States. Four commercial airplanes were hijacked; two were flown into the World Trade Center towers in New York City, causing both towers to collapse. A third plane struck the Pentagon in Arlington, Virginia, while the fourth, United Airlines Flight 93, crashed in a field in Pennsylvania after passengers attempted to regain control from the hijackers. The attacks resulted in the deaths of nearly 3,000 people and caused significant destruction. In response, the U.S. government launched the War on Terror, leading to military operations in Afghanistan aimed at dismantling al-Qaeda and removing the Taliban from power. The events of September 11 have had a lasting impact on global security policies and international relations.