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.
Responsibility for the September 11 attacks
According to interviews by Al-Jazeera as well as United States interrogations of al-Qaeda members Ramzi bin al-Shibh and Khalid Shaikh Mohammed (captured in 2002 and 2003 respectively), Khalid Sheikh Mohammed was the instigator and prime organizer of the attacks. Bin al-Shibh may have been picked as a hijacker but he failed to get into the United States.