Bush: No evidence attacks were preventable

WASHINGTON (CNN) -- Despite communication breakdowns between the CIA and FBI before the September 11 attacks, there is no evidence suggesting the U.S. government could have prevented the strikes, President Bush said Tuesday.

Bush also said Congress should conduct one focused investigation -- not several reviews -- so law enforcement and intelligence officials are not distracted from their work.

"What I am concerned about is tying up valuable assets and time and possibly jeopardizing sources of intelligence," Bush told reporters Tuesday during a tour of the National Security Agency.

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His remarks came as the House and Senate intelligence committees opened a joint hearing into what the government knew about the risk of a terrorist strike before September 11 and how that information was -- or wasn't -- shared among government agencies.

Bush was asked about the failure of the FBI and CIA to share information about terror threats, including movements of and suspicions about those ultimately involved in the hijackings.

"In terms of whether the FBI and CIA were communicating properly, I think it is clear that they weren't," he said. "Now we have addressed that issue. The CIA and FBI are now in close communication."

He downplayed talk of finger-pointing between the FBI and CIA, saying he believed it was from "level 3 staffers trying to protect their hides."

"I am concerned about distractions from this perspective: I want the Congress to investigate, but I want a committee to investigate, not multiple committees to investigate. ... I don't want to tie up our team when we are trying to fight this war on terror," Bush said.

Critics suggest the White House is wary of several investigations and public hearings because it fears the evidence will reveal multiple examples of intelligence and communications failures.

The White House also opposes a special commission to review what the government knew before September 11. In supporting the joint review by the intelligence committees, it has urged that the overwhelming majority of its proceedings be kept secret on grounds that sensitive intelligence data and methods need to be protected.