For me, the "Aha" moment occurred the first time I read the 9/11 Commission Report and saw the veiled admissions that warnings were ignored in chapter 8, entitled "The System Is Blinking Red", and for others it may be the recent review of the July 2001 news story as unearthed by Blue Meme at dailykos.
Bob Woodward in his latest book State of Denial, relates the timeline that Condescenda Rice was told on July 10, 2001 that the FBI and CIA had increased the threat assessment for a terrorist attack on US assets. She asked that Attorney General John Ashcroft be given the same presentation, which he was then given on July 17 according to official logs.
Blue Meme points out this news story from CBS from July 26, 2001 that Ashcroft had abruptly stoppped flying commercial airlines and instead chartered private jets, at a cost of $1600 per hour to taxpayers, immediately after that presentation:
In response to inquiries from CBS News over why Ashcroft was traveling exclusively by leased jet aircraft instead of commercial airlines, the Justice Department cited what it called a "threat assessment" by the FBI, and said Ashcroft has been advised to travel only by private jet for the remainder of his term.Why? We were never told.
Bush's cabinet members were changing their normal travel behaviors in apparent direct response to the same information outlined only now in Woodward's book. Instead of warning the public and casting a wide net, Bush was preoccupied with pilfering the US Treasury of tax cuts for the upper class and spendng a full month clearing brush from his Texas faux ranch.