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.
9/11 Commission Report
In addition to identifying intelligence failures occurring before the attacks, the report provided evidence of the following:The commission also concluded 15 of the 19 hijackers who carried out the attacks were from Saudi Arabia, but the commission "found no evidence that the Saudi government as an institution or senior Saudi officials individually funded the organization" to conspire in the attacks, or that it funded the attackers even though the "report identifies Saudi Arabia as the primary source of al-Qaeda funding". (A 28-page section of an earlier, different 9/11 report included claims of greater Saudi involvement, but "did not withstand deeper scrutiny" by the Commission.)
Mohamed Atta, the leader of the attacks, was from Egypt. Two hijackers were from the United Arab Emirates, and one was from Lebanon. According to the commission, all 19 hijackers were members of the al-Qaeda terrorist organization, led by Osama bin Laden. In addition, while meetings between al-Qaeda representatives and Iraqi government officials had taken place, the panel had no credible evidence that Saddam Hussein had assisted al-Qaeda in preparing or executing the 9/11 attacks.