The Pentagon inspector general's office said Thursday that a review of records from the unit, known as Able Danger, found no evidence it had identified ringleader Mohamed Atta or any other terrorist who participated in the 2001 attacks.
The report was ordered following the assertion that four of the 19 hijackers were identified in 2000 by a classified military intelligence unit known as "Able Danger."
Weldon, R-Pa., said the unit used data mining to link ringleader Mohamed Atta and three other hijackers to al Qaeda more than a year before the attacks of Sept. 11, 2001.
Weldon questioned the "motives and the content" of the report and rejected its conclusions. "Acting in a sickening bureaucratic manner, the DOD IG cherry-picked testimony from witnesses in an effort to minimize the historical importance of the Able Danger effort," Weldon said in a statement.
"The report trashes the reputations of military officers who had the courage to step forward and put their necks on the line to describe important work they were doing to track al-Qaida prior to 9/11," Weldon said. He said the investigation did little to answer the questions it was supposed to examine.
He also said the intelligence unit wanted the information given to the FBI, but that Pentagon lawyers rejected the recommendation.
The report acknowledged that one Able Danger member alleged he was prohibited from providing a chart to the FBI in 2000 by a senior Special Operations commander. But, the report said, "the senior official did not recall the incident and we are persuaded that the chart would have been of minimal value to the FBI."
The Pentagon had said some employees recall seeing an intelligence chart identifying Atta as a terrorist before the attacks. The report said those accounts "varied significantly" and witnesses were inconsistent at times in their statements.
Several lawmakers had asked the Pentagon to investigate whether Defense Department officials mismanaged Able Danger and retaliated against Shaffer. He was a leading proponent of the program who later had his security clearance revoked.
The report said Shaffer was not retaliated against because of his involvement. But the inspector general did find "procedural oversights" in the handling of his office contents and his performance evaluations.
A message left with Shaffer's lawyer was not returned immediately on Thursday.
Last year, the bipartisan commission that investigated the attacks dispensed with the issue by calling it "not historically significant."
Thomas Kean, the commission's co-chairman, said he hoped the report would put an end to discussion about Able Danger. "After this I don't know where it can go," Kean said.