White House spokesman Ari Fleischer confirmed that Bush had been told about the possibility of hijackings but he declined to say what had been revealed during his intelligence briefings.
"There was . . . an awareness by the government, including the president, of Osama bin Laden and the threat he posed in the United States and around the world," Fleischer said. "That included long-standing speculation about hijacking in the traditional sense, but not involving suicide bombers using airplanes as missiles."
A CIA spokesman said the agency routinely passed on intelligence citing the possibility that al Qaeda might be planning to hijack an airliner as part of a terrorist action against the United States. But a suicide attack involving an aircraft was never envisioned, the spokesman said.
The intelligence briefing on al Qaeda hijackings, first reported last night by CBS News, marks the most detailed disclosure of what Bush was told about the possibility of terror attacks before Sept. 11. It also represents a shift in the official version of events surrounding the attacks on New York and Washington, which Bush and other administration officials have generally characterized as a sneak attack that could not have been foreseen by U.S. intelligence.
"It's hard to envision a plot so devious as the one that they pulled off on 9/11," Bush said in a January interview with NBC's Tom Brokaw. "Never did we realize that the enemy was so well organized."
The new information adds to the debate over whether more could have been done to halt the attacks.Congress is conducting an inquiry into possible intelligence failures before the attacks.
The information provided to Bush was included as part of the president's daily briefing, a highly restricted classified document prepared by the CIA. The document is seen by only a handful of people, White House officials said: Bush, Vice President Cheney, CIA Director George J. Tenet, national security adviser Condoleezza Rice and, less frequently, Chief of Staff Andrew H. Card Jr.
Sen. Bob Graham (D-Fla.) said yesterday that he has been told of a CIA document that reached Bush in August, warning him of a more specific al Qaeda attack involving an airliner. Graham, chairman of the Senate intelligence committee, said he had not yet read the document, but that congressional staffers have.
Until now, the growing congressional scrutiny of possible warning signs before Sept. 11 has focused on the FBI's actions, including the bureau's handling of a memo written in July 2001 by an agent in Phoenix. A senior U.S. official who has reviewed the classified memo said yesterday that the FBI agent had made a "strong connection" between a group of Middle Eastern aviation students he was investigating and Osama bin Laden's al Qaeda network. The link was included in the five-page memorandum sent to FBI headquarters two months before the attacks.
The agent was so concerned that he mentioned bin Laden in the first sentence of the memo, which suggested that terrorists from al Qaeda or other groups might be using flight schools to prepare for a hijacking or bombing plot, several officials said.
The new details heightened a controversy that developed two weeks ago, when the outline of the agent's memo surfaced in news reports.
FBI Director Robert S. Mueller III told a Senate committee last week that he wished the agency had been more aggressive in following up on the memo. But Mueller said doing so would not have led investigators to the Sept. 11 plot, and that none of the aviation students has been connected to the hijackings.
The Phoenix office's concerns were never relayed to a separate group of FBI agents in Minnesota, who were scrambling to determine the intentions of French national Zacarias Moussaoui. Moussaoui had been arrested at a flight school in August after he had aroused school officials' suspicions. It was only later that the FBI concluded that Moussaoui, now under indictment, was part of the hijacking conspiracy.
FBI officials have repeatedly declined to release the entire memorandum, citing its classified status and providing only a one-paragraph portion that describes the agent's suggestion that flight schools nationwide be canvassed for Middle Easterners. It remained unclear yesterday exactly what led the agent to make a link between al Qaeda and the students he was investigating from Embry-Riddle Aeronautical University in Prescott, Ariz. But one source said the memo was "thorough" in outlining his concerns.
As details emerged, criticism of the FBI intensified on Capitol Hill.
Sen. Richard C. Shelby (R-Ala.), the ranking minority member of the Intelligence Committee, yesterday said the Phoenix agent's memo "was a very important warning and it was not heeded. It was not distributed. It was not acted upon."
"That in itself is a damning piece of evidence of the FBI losing an opportunity," Shelby said. Combined with the Bush briefing and "events in Minnesota five weeks later, it's more than damning," he said. "Why didn't the FBI link them? They were either asleep, or inept, or both. What more is it going to take to wake up the FBI?"
Shelby is a leader of a joint House and Senate investigation into the attacks and the performance of the FBI, CIA and other agencies.
Three of the Sept. 11 hijackers received training from U.S. flight schools, although none was enrolled at the time of the July 10 memo, officials said. None received training at Embry-Riddle, although Flight 77 suicide pilot Hani Hanjour may have practiced on a flight simulator of a school in Phoenix.
During his Senate appearance last week, Mueller stressed that none of those under investigation in Arizona has since been connected to the attacks.
That point was reinforced yesterday by Fleischer, who said at a news briefing yesterday that Bush agreed with Mueller that the memo "in and of itself would not have led to the prevention of the September 11th attacks."
Sen. Richard J. Durbin (D-Ill.), a member of the Intelligence Committee who has read the memo "several times," said yesterday that the memo "was very explicit in terms of connecting suspected terrorists in the United States with aviation training schools. That should have been a red flag."
Durbin also said sentiment is growing in Congress for the Bush administration to release the memo, or at least hold classified briefings on it.
Sen. Charles E. Grassley (R-Iowa) sent a letter to Mueller yesterday demanding public release of the memo "to demonstrate that the FBI has nothing to hide and that from this point forward, candor and straight talk will be the FBI's mode of operation."
Grassley said in an interview that the reference to bin Laden "is so obvious that it should have gotten more attention."
Staff writers Mike Allen and Dana Priest contributed to this report.