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.
1993 World Trade Center bombing
The 1993 World Trade Center bombing was a terrorist attack on the World Trade Center, carried out on February 26, 1993, when a truck bomb detonated below the North Tower of the World Trade Center in New York City. The urea nitrate–hydrogen gas enhanced device was intended to send the North Tower (Tower 1) crashing into the South Tower (Tower 2), bringing both towers down and killing tens of thousands of people. It failed to do so but killed six people and injured over a thousand.