The September 11 attacks were a series of four coordinated suicide attacks upon the United States in New York City and Washington, D.C. on September 11, 2001. On that morning, 19 terrorists from the Islamist militant group al-Qaeda hijacked four passenger jets. The hijackers intentionally crashed two planes, American Airlines Flight 11 and United Airlines Flight 175, into the Twin Towers of the World Trade Center in New York City; both towers collapsed within two hours. Hijackers crashed American Airlines Flight 77 into the Pentagon in Arlington, Virginia. The fourth jet, United Airlines Flight 93, crashed into a field near Shanksville, Pennsylvania after passengers attempted to take control before it could reach the hijacker's intended target in Washington, D.C. Nearly 3,000 died in the attacks.

Terroranschläge am 11. September 2001. Attentati dell'11 settembre 2001. Terrorangrepet 11. september 2001. 九一一袭击事件 Attentats du 11 septembre 2001.