Why did Attorney General John Ashcroft and some Pentagon officials cancel commercial-airline trips before Sept. 11?

On July 26, 2001 - 47 days before the Sept. 11 attacks - CBS News reported that Ashcroft was flying expensive charters rather than commercial flights because of a "threat assessment" by the FBI. CBS said, "Ashcroft has been advised to travel only by private jet for the remainder of his term." Newsweek later reported that on Sept. 10, 2001, "a group of top Pentagon officials suddenly canceled travel plans for the next morning, apparently because of security concerns."

Did either Ashcroft or the Pentagon have advance information about a 9/11-style attack and, if so, why wasn't this shared with the American public?

19 other pertinent unanswered questions are speculated about here.

This is old news, like the news that Iraq is paying 90 cents a gallon for fuel transported from Kuwait by Halliburton, when the average wholesale cost of gasoline in the Middle East is more like 71 cents anywhere else. At least I think I have that right. I read it like ten minutes ago, so I could possibly have had enough time to jumble it up. Anyway, I learned about all this and more through the lovely people at anybodybutbush, who appear to be having it going on, as they say.