They knew, but did nothing
Even reporters in Washington who covered intelligence issues acknowledged they were largely ignorant that summer that the CIA and other parts of the Government were warning of an almost certain terrorist attack. Probably, but not necessarily, overseas.
The warnings were going straight to President Bush each morning in his briefings by the CIA director, George Tenet, and in the presidential daily briefings. It would later be revealed by the 9/11 commission into the September 11 attacks that more than 40 presidential briefings presented to Bush from January 2001 through to September 10, 2001, included references to bin Laden.
And nearly identical intelligence landed each morning on the desks of about 300 other senior national security officials and members of Congress in the form of the senior executive intelligence brief, a newsletter on intelligence issues also prepared by the CIA.
The senior executive briefings contained much of the same information that was in the presidential briefings but were edited to remove material considered too sensitive for all but the President and his top aides to see. Often the differences between the two documents were minor, with only a sentence or two changed between them. Apart from the commission's chief director, Philip Zelikow, the commission's staff was never granted access to Bush's briefings, except for the notorious August 2001 briefing that warned of the possibility of domestic al-Qaeda strikes involving hijackings. But they could read through the next best thing: the senior executive briefings.
http://www.smh.com.au/news/world/they-knew-but-did-nothing/2008/03/07/1204780065676.html