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.
William Rodriguez
Rodriguez also claimed to have seen hijacker Mohand al-Shehri scoping out the building prior to the attacks, in June 2001. A "Daily News" article says he told the FBI and the 9/11 Commission that he recognized the man after a brief, chance encounter months prior to the terrorist attacks. "It is believed that American Airlines Flight 11 hijacker Mohamed Atta cased New York City targets, including the Diamond District, but Rodriguez may have given the 9/11 panel the first eyewitness testimony about a hijacker inside one of the towers before the terror strike.