What sets this type of operation apart from the unprecedented covert domestic spying activities the NSA had been conducting after 9/11 is a top secret executive order signed by President Bush in 2002 authorizing the NSA to target specific American citizens. Prior to 9/11, American citizens were the subject of non-specific surveillance by the NSA that was condoned and approved by President Bush, Vice President Dick Cheney, and Secretary of Defense Donald Rumsfeld, according to former NSA and counterterrorism officials.

The sources, who requested anonymity because they were instructed not to talk about NSA activities but who hope they can testify before Congress about the domestic spying, said that in December 2000, the NSA completed a report for the incoming administration titled "Transition 2001," which explained, among other things, how the NSA would improve its intelligence gathering capabilities by hiring additional personnel.

Moreover, in a warning to the incoming administration, the agency said that in its quest to compete on a technological level with terrorists who have access to state-of-the-art equipment, some American citizens would get caught up in the NSA's surveillance activities. However, in those instances, the identities of the Americans who made telephone calls overseas would be "minimized," one former NSA official said, in order to conceal the identity of the American citizen picked up on a wiretap.

"What we're supposed to do is delete the name of the person," said the former NSA official, who worked as an encryption specialist.

The former official said that even during the Clinton administration, the NSA would inadvertently obtain the identities of Americans citizens in its wiretaps as a result of certain keywords, like bomb or jihad, NSA computers are programmed to identify. When the NSA prepares its reports and transcripts of the conversations, the names of Americans are supposed to be immediately destroyed.

By law, the NSA is prohibited from spying on a United States citizen, a US corporation or an immigrant who is in this country on permanent residence. With permission from a special court, the NSA can eavesdrop on diplomats and foreigners inside the US.

"If, in the course of surveillance, NSA analysts learn that it involves a US citizen or company, they are dumping that information right then and there," an unnamed official told the Boston Globe in a story published October 27, 2001.

But after Bush was sworn in as president, the way the NSA normally handled those issues started to change dramatically. Vice President Cheney, as Bob Woodward noted in his book Plan of Attack, was tapped by Bush in the summer of 2001 to be more of a presence at intelligence agencies, including the CIA and NSA.

"Given Cheney's background on national security going back to the Ford years, his time on the House Intelligence Committee, and as secretary of defense, Bush said at the top of his list of things he wanted Cheney to do was intelligence," Woodward wrote in his book about the buildup to the Iraq war. "In the first months of the new administration, Cheney made the rounds of the intelligence agencies - the CIA, the National Security Agency, which intercepted communications, and the Pentagon's Defense Intelligence Agency. "

It was then that the NSA started receiving numerous requests from Cheney and other officials in the state and defense departments to reveal the identities of the Americans blacked out or deleted from intelligence reports so administration officials could better understand the context of the intelligence.

Separately, at this time, Cheney was working with intelligence agencies, including the NSA, to develop a large-scale emergency plan to deal with any biological, chemical or nuclear attack on US soil.

Requesting that the NSA reveal the identity of Americans caught in wiretaps is legal as long as it serves the purpose of understanding the context of the intelligence information.

But the sources said that on dozens of occasions Cheney would, upon learning the identity of the individual, instruct the NSA to continue monitoring specific Americans caught in the wiretaps if he thought more information would be revealed, which crossed the line into illegal territory.

Cheney advised President Bush of what had turned up in the raw NSA reports, said one former White House official who worked on counterterrorism related issues.

"What's really disturbing is that some of those people the vice president was curious about were people who worked at the White House or the State Department," one former counterterrorism official said. "There was a real feeling of paranoia that permeated from the vice president's office and I don't think it had anything to do with the threat of terrorism. I can't say what was contained in those taps that piqued his interest. I just don't know."

An NSA spokesperson would not comment for this story. Because of the level of secrecy at the agency, it's impossible to ascertain for the record how far the agency has gone in its domestic surveillance.

James Bamford, the author of the bestselling books The Puzzle Palace and Body of Secrets, which blew the door wide open by first revealing the NSA's covert activities, said he doesn't believe terrorism was a priority for the administration before 9/11 and he doesn't think the agency targeted specific Americans as it is doing now.

"I looked into that theory," Bamford said in an interview. "And I was assured that domestic surveillance was a black area the NSA stayed away from before 9/11. The NSA was sort of a side agency before 9/11. At that point they were looking for a mission. Terrorism was not a big priority. (American) names may have been picked up but I was told they dropped them immediately after. That's the procedure."

But Bamford said it's possible the NSA may have conducted the type of spying prior to 9/11 that the former NSA officials described. "It's hard to tell" if that happened, Bamford said. "It's a very secret agency."

In the summer of 2001, the NSA spent millions of dollars on a publicity campaign to repair its public image by taking the unprecedented step of opening up its headquarters in Fort Meade, Maryland to reporters, to dispel the myth that the NSA was spying on Americans.

In a July 10, 2001, segment on "Nightline," host Chris Bury reported that "privacy advocates in the United States and Europe are raising new questions about whether innocent civilians get caught up in the NSA's electronic web."

Then-NSA Director Lt. Gen. Michael Hayden, who was interviewed by "Nightline," said it was absolutely untrue that the agency was monitoring Americans who are suspected of being agents of a foreign power without first seeking a special warrant from the Foreign Intelligence Surveillance Court.

"We don't do anything willy-nilly," Hayden said. "We're a foreign intelligence agency. We try to collect information that is of value to American decision-makers, to protect American values, America - and American lives. To suggest that we're out there, on our own, renegade, pulling in random communications, is - is simply wrong. So everything we do is for a targeted foreign intelligence purpose. With regard to the - the question of industrial espionage, no. Period. Dot. We don't do that."

But, when asked "How do we know that the fox isn't guarding the chicken coop?" Hayden responded by saying that Americans should trust the employees of the NSA.

"They deserve your trust, but you don't have to trust them," Hayden said. "We aren't off the leash, so to speak, guarding ourselves. We have a body of oversight within the executive branch, in the Department of Defense, in the president's Foreign Intelligence Advisory Board, which is comprised of both government and nongovernmental officials. You've got both houses of Congress with - with very active - in some cases, aggressive - intelligence oversight committees with staff members who have an access badge to NSA just like mine."

One former NSA official said in response to Hayden's 2001 interview, "What do you expect him to say? He's got to deny it. I agree. We weren't targeting specific people, which is what the President's executive order does. However, we did keep tabs on some Americans we caught if there was an interest" by the White House. "That's not legal. And I am very upset that I played a part in it."

James Risen, the New York Times reporter credited with exposing the NSA's covert domestic surveillance activities that came as a result of a secret executive order President Bush issued in 2002, wrote in his just-published book, State of War, that the administration was very aggressive in its intelligence gathering activities before 9/11. However, Risen does not say that means the administration permitted the NSA to spy on Americans.

"It is now clear that the White House went through the motions of the public debate over the (2001) Patriot Act, all the while knowing that the intelligence community was secretly conducting a far more aggressive domestic surveillance campaign," Risen wrote in State of War.

Jason Leopold is the author of the explosive memoir, NEWS JUNKIE, to be published in April on Process/Feral House books.