The Pentagon is pressuring the Senate Judiciary Committee to close to the public next week's hearings on a former secret military intelligence unit called "Able Danger," two congressional sources have confirmed to FOX News.

Witnesses from the Pentagon are expected to testify at that hearing; that's why they want it classified. FOX News has learned that committee Chairman Arlen Specter's office is vigorously resisting the request.

Some former Able Danger analysts and Rep. Curt Weldon (search) say the formerly clandestine intelligence unit identified Mohammed Atta (search) and three other of the Sept. 11, 2001, hijackers one year before the attacks that left over 3,000 people dead. They also claim that their repeated requests to turn over the information to the FBI were ignored.

Weldon said a former Army officer will testify next week that he was also ordered to destroy data that included reference to Atta.

"In the summer of 2000, he was ordered and, or, he would go to jail if he didn't comply," the Pennsylvania Republican said. "He was ordered to destroy 2.5 terabytes of data specific to Able Danger, the Brooklyn [terror] cell and Mohammad Atta. He will name the person who ordered him to destroy that material."

Other witnesses will include an FBI agent who will testify that she set up three meetings in 2000 between the FBI's Washington field office and the Able Danger, but each was cancelled at the last minute, Weldon said.

The Pentagon has changed its position on this story, from originally questioning the very existence of Able Danger (search) to now confirming that the Defense Department has identified five former members of the unit who all say they remember Atta's picture or name, on a chart in 2000.

Weldon wrote a letter over the summer that ignited a debate over what the Sept. 11 commission (search) probing the attacks knew or didn't know about the intelligence group, and whether it ignored evidence that would have helped shed light on the timeline of investigations into the hijackers' presence in the United States. The commission also has been criticized for not including the Able Danger project in their report last summer.

"The Sept. 11 commission's statement that it does not believe a secret military intelligence unit discovered a group of future hijackers more than a year before the terrorist attacks is "a total denial of the facts," Weldon said Thursday. "For the 9/11 commission to say that this did not exist is just absolutely outrageous. It's a total denial of the facts."

The commission's chairman, Thomas Kean, said that the panel had acquired no evidence anyone in the government knew about lead hijacker Atta before Sept. 11, 2001.

According to Weldon and several members of Able Danger, the secret group identified Atta and three other hijackers as potential members of a terrorist cell in New York City. Weldon and the Able Danger analysts — Army Lt. Col. Anthony Shaffer (search) and Navy Capt. Scott Phillpott (search) — maintain that Pentagon lawyers rejected the unit's recommendation that the information be turned over to the FBI in 2000 based on immigration rules at the time.

Shaffer and Phillpott also say they met with staff members on the Sept. 11 commission about their findings. But commission members have denied that Atta was mentioned by name at those meetings, some of which were in October of 2002.

While the Pentagon says Shaffer and Phillpott are credible, the Defense Department says it has found no documents to back up their claims. However, the Pentagon confirmed this month that documents associated with Able Danger were destroyed because of strict regulations governing the collection of data on foreign visitors in the United States.

The National Commission on Terrorist Attacks on the United States, informally called the Sept. 11 commission, was set up in 2002 to investigate pre-attack intelligence and communication failures between U.S. law enforcement and spy agencies. On Wednesday, former members of the Sept. 11 commission said they weren't buying the story that the Able Danger group identified the hijackers so early.

"Bluntly, it just didn't happen and that's the conclusion of all 10 of us," said Sept. 11 commissioner Slade Gorton, a former Republican senator from Washington state.

The panel had appeared at a news conference to argue that the response to Hurricane Katrina (search) might have been more successful if more of the recommendations it had made last year had been implemented.

During the press event, the commissioners criticized the government for not putting in place changes recommended last year for homeland security and emergency response. They pointed most notably to the failure to improve communication systems, which they said might have saved lives after Hurricane Katrina.

"It is a scandal in our minds that four years after Sept. 11, we have not yet set aside radio spectrum to insure that police, firefighters and emergency medical technicians can communicate reliably during any kind of attack or any kind of major disaster," Kean said.

The commissioners also faulted state, local and federal authorities responding to Katrina for not having a clear chain of command, leading to some of the same confusion that plagued the Sept. 11 rescue effort.

"Many of these recommendations proposed by the Sept. 11 commission one year ago might have made a difference in saving lives and preventing loss of lives in this hurricane," said member Tim Roemer, a former Democratic congressman from Indiana.

The commissioners, who now belong to the Sept. 11 Discourse Project (search) to oversee the translation of their recommendations into reality, also played down claims by the Defense Department's secret intelligence unit.

Earlier this month, the Pentagon confirmed in a briefing that it had identified five people involved with Able Danger who claimed they had either seen a picture of Atta or had seen his name on a chart prepared in 1999 by the intelligence unit. It was the first extensive briefing by Pentagon officials since questions about Able Danger began circulating last month.

But while Pentagon officials call these sources credible, they say that after interviewing some 80 individuals associated with Able Danger and reviewing hundreds of thousands of documents, they still have not found such a chart and don't even know if it exists. The Pentagon said that documents associated with the project had been destroyed.

The Defense Department did confirm that documents associated with Able Danger were destroyed in accordance with strict regulations about collection, dissemination and destruction procedures for intelligence gathered on people inside the United States.The officials denied that military lawyers ordered the destruction of the documents.

Navy Commander Christopher Chope of the U.S. military's Special Operations Command added that the Pentagon investigation found no evidence to back up claims that the military refused to share key information gleaned by Able Danger with the FBI.

While the document review is now over, the Pentagon says it continues to interview and re-interview people associated with the program.

FOX News' Catherine Herridge and The Associated Press contributed to this report.