According to both this NY Times and this Globe & Mail story about the same thing, Junior was advised of the Al-Qaeda threat before 9/11. For what it's worth -- given the media's ability to get things wrong or "mistaken" is a snip:
Crawford, Tex. — U.S. President George W. Bush was told more than a month before the Sept. 11 attacks that al-Qaeda had reached America's shores, had a support system in place for its operatives and that the FBI had detected suspicious activity that might involve a hijacking plot.That would imply negligence in command to augment the decisiveness in action after the fact