U.S. President George W. Bush says America's law enforcement and spy agencies did not coordinate information well enough prior to the September 11 terrorist attacks. But he also says he has seen nothing that indicates those attacks could have been prevented.

The president's commments came shortly before closed-door hearings began on Capitol Hill, where members of the House and Senate Intelligence Committees were to proble whether the FBI, CIA and other agencies missed clues that could have prevented the terrorist attacks.

Mr. Bush acknowledges these agencies did not communicate well before September 11, saying "I think it is clear that they were not, and now we have addressed that issue. And the CIA and FBI are now in close communication."

Mr. Bush stresses that despite the lack of coordination prior to the attacks, he has seen nothing that indicates America could have thwarted the terrorist plot.

The president spoke during a visit to the top-secret National Security Agency, which intercepts and analyzes global communications. It plays a far less visible role in the intelligence community than the CIA and the FBI.

Standing before a banner that read "We won't back down. We never have. We never will," Mr. Bush reaffirmed his confidence in the men and women who work for these agencies. He said their morale is high, and their work is crucial.

"Our intelligence communities understand they are on the forefront of one of the most important wars in the nation's history," he said.

The president said he supports the joint investigation being conducted by the House and Senate Intelligence Committees. But he said he is worried that other congressional panels will launch their own inquiries, and these agencies could be hit with a flood of requests for testimony and information. "What I am concerned about is tying up valuable assets and time," he said, "and possibly jeopardizing sources of intelligence." The president said he does not want to distract people whose job is to prevent another terrorist attack.