It was perhaps the most famous presidential briefing in history. On Aug. 6, 2001, President George W. Bush received a classified review of the threats posed by Osama bin Laden and his terrorist network, Al Qaeda. That morning's presidential daily brief" - the top-secret document prepared by America's intelligence agencies - featured the now-infamous heading: "Bin Laden Determined to Strike in U.S." On April 10, 2004, the Bush White House declassified that daily brief - and only that daily brief - in response to pressure from the 9/11 Commission. [But] the Aug. 6 document, for all of the controversy it provoked, is not nearly as shocking as the briefs that came before it. The direct warnings to Mr. Bush about the possibility of a Qaeda attack began in the spring of 2001. By May 1, the Central Intelligence Agency told the White House of a report that "a group presently in the United States" was planning a terrorist operation. Weeks later, on June 22, the daily brief reported that Qaeda strikes could be "imminent," although intelligence suggested the time frame was flexible. Operatives connected to Bin Laden, one [warning] reported on June 29, expected the planned near-term attacks to have "dramatic consequences," including major casualties. Yet, the White House failed to take significant action. In the aftermath of 9/11, Bush officials attempted to deflect criticism that they had ignored C.I.A. warnings by saying they had not been told when and where the attack would occur.