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.
Presidency of George W. Bush
On September 11, 2001, al-Qaeda terrorists hijacked four airliners and flew two them into the twin towers of the World Trade Center in New York City, destroying both 110-story skyscrapers. Another plane crashed into Pentagon, while the final plane was brought down in Pennsylvania following a struggle between the terrorists and the aircraft's passengers. The attacks had a profound effect on many Americans, who felt vulnerable to international attacks for the first time since the end of the Cold War. Appearing on national television on the night of the attacks, Bush promised to punish those who had aided the attacks, stating, "we will make no distinction between the terrorists who committed these acts and those who harbor them." In the following days, Bush urged the public to renounce hate crimes and discrimination against Muslim-Americans and Arab-Americans. He also declared a "War on Terror", instituting new domestic and foreign policies in an effort to prevent future terrorist attacks.