Donald Rumsfeld
The United States was attacked on September 11, 2001 by al Qaeda terrorists who hijacked commercial airliners and crashed them in coordinated strikes into both towers of the World Trade Center in Lower Manhattan, New York City and the Pentagon in Washington, D.C. The fourth plane crashed into a field in Shanksville, Pennsylvania, and its target was likely a prominent building in Washington, D.C., most probably either the Capitol Building or the White House. Within three hours of the start of the first hijacking and two hours after American Airlines Flight 11 struck the World Trade Center, Rumsfeld raised the defense condition signaling of the United States offensive readiness to DEFCON 3, the highest it had been since the Arab-Israeli war in 1973.
Motives for the September 11 attacks
The September 11, 2001, attacks in the northeast United States were an organized terrorist act carried out by 19 hijackers, and organized by numerous members of al-Qaeda. Motives for the attacks were stated before and after the attacks in several sources, Osama bin Laden's declaration of a holy war against the United States, and a fatwā signed by bin Laden and others for the killing of Americans in 1998, are seen by investigators as evidence of his motivation. However, in an interview with Daily Ummat, Osama bin Laden rejected Al-Qaeda's involvement in the September 11 attacks.