Shortly after September 11, 2001, the National Security Agency began sending intelligence data on people suspected of ties to terrorist groups to the Federal Bureau of Investigation. We now know that that data came from a controversial surveillance program in which people in the U.S. were placed under surveillance. What is new is that virtually all of this data is junk.

FBI officials told the New York Times that virtually all of the leads provided them under the NSA domestic surveillance program turned out to be “dead ends.”

“We’d chase a number, find it’s a schoolteacher with no indication they’ve ever been involved in international terrorism — case closed,” one such FBI official, who was aware of the NSA program, told the Times. “After you get a thousand numbers and not one is turning up anything, you get some frustration.”

FBI officials familiar with the program say it diverted resources to wild goose chases, preventing them from doing more productive counterterrorism work.

Of course, intelligence officials disagreed with the assessment of the program’s output.

“I can say unequivocally that we have gotten information through this program that would not otherwise have been available,” General Hayden said. The White House and the F.B.I. declined to comment on the program or its results.

The differing views of the value of the N.S.A.’s foray into intelligence-gathering in the United States may reflect both bureaucratic rivalry and a culture clash. The N.S.A., an intelligence agency, routinely collects huge amounts of data from across the globe that may yield only tiny nuggets of useful information; the F.B.I., while charged with fighting terrorism, retains the traditions of a law enforcement agency more focused on solving crimes.

“It isn’t at all surprising to me that people not accustomed to doing this would say, ‘Boy, this is an awful lot of work to get a tiny bit of information,’ ” said Adm. Bobby R. Inman, a former N.S.A. director. “But the rejoinder to that is, Have you got anything better?”

Several of the law enforcement officials acknowledged that they might not know of arrests or intelligence activities overseas that grew out of the domestic spying program. And because the program was a closely guarded secret, its role in specific cases may have been disguised or hidden even from key investigators.

Still, the comments on the N.S.A. program from the law enforcement and counterterrorism officials, many of them high level, are the first indication that the program was viewed with skepticism by key figures at the Federal Bureau of Investigation, the agency responsible for disrupting plots and investigating terrorism on American soil.

All the officials spoke on condition of anonymity because the program is classified. It is coming under scrutiny next month in hearings on Capitol Hill, which were planned after members of Congress raised questions about the legality of the eavesdropping. The program was disclosed in December by The New York Times. — New York Times

The very few valid leads coming out of the program, less than one in a thousand, were mostly people the FBI already knew about, the officials said. Moreover, the program turned up no evidence of al-Qaeda networks or plots operating in the United States, they said.

What a waste. Countless thousands of American people’s calls monitored, virtually all of them having nothing at all to do with terrorists. This is fairly close to the worst case scenario we suspected all along. The only way it could be worse is to find out that those innocent Americans were targeted for their political beliefs. I’m still waiting for that shoe to drop.