After coming under investigation over an alleged pattern of misconduct while deployed as a staff officer in Afghanistan, Shaffer responded by alleging that the U.S. Defense Intelligence Agency (DIA) failed to properly evaluate intelligence on 9/11 hijacker Mohamed Atta. Shaffer's allegations subsequently became known as the Able Danger. In October 2003, according to his later statement to Congress, Shaffer told the 9/11 Commission staff director, Dr. Philip D. Zelikow, that in 2000 a DIA data-mining program known as Able Danger had uncovered two of the three terrorist cells eventually implicated in the September 11 attacks. Shaffer reportedly told Zelikow that DIA leadership declined to share this information with the FBI because military lawyers expressed concerns about the legality of doing so. Shaffer also asserted that he briefed Director of Central Intelligence George Tenet on three separate occasions regarding his unit's activities. The 9/11 Commission Report did not mention Shaffer's allegations, but in 2005 and 2006 the Chairman of the House Select Intelligence Committee, Rep. Curt Weldon, publicized Shaffer's allegations in public statements and hearings.
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