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.
New York City landmark bomb plot
After the World Trade Center bombing, the Federal Bureau of Investigation had a confidential informant, Emad Salem, infiltrate the group of plotters. FBI officers arrested the main suspects in June 1993 before the plot could be carried out. In 1995, ten defendants were convicted of 48 charges related to the plot.