On September 11, 2001, nineteen Islamic radicals conducted the worst terrorist strike on American soil. They hijacked four commercial airliner jets and crashed two airplanes into the Twin Towers of the World Trade Center in New York City, killing more than three thousand people. They crashed another plane into the Pentagon, killing nearly two hundred people. A fourth plane crashed in Pennsylvania due to the heroic efforts of the passengers who lost their lives when they stormed the attackers, diverted the plane from its probable destination of Washington, D.C., and saved an untold number of lives in the process.

The hijackers were all members of the terrorist group al-Qaeda, led by Osama Bin Laden. The United States and others responded with a global War on Terror and sought to cripple al-Qaeda. Bin Laden was finally located hiding in a fortified Pakistan hideout in May 2011. U.S. Navy Seals shot him to death.