The September 11 Attacks

The September 11 attacks were a coordinated series of terrorist attacks carried out on 11 September 2001 by nineteen militants affiliated with the Islamist extremist network al-Qaeda, who hijacked four commercial airliners in the United States. Two of the aircraft were flown into the twin towers of the World Trade Center in New York City, causing both towers to collapse; a third was flown into the Pentagon near Washington, D.C.; and a fourth, believed to have been headed for a target in the capital, crashed into a field near Shanksville, Pennsylvania, after passengers attempted to retake control of the aircraft. The attacks killed nearly three thousand people and remain the deadliest terrorist attack in history by death toll. In their aftermath the United States declared a global War on Terror, invading Afghanistan later in 2001 to remove the Taliban government that had sheltered al-Qaeda's leadership, and the attacks reshaped international security policy, air travel security, and American foreign policy for the following two decades, including the later, more contested invasion of Iraq in 2003.