In addition to the material captured by Fariscal, which outlined an attack using airliners as flying bombs, the CIA had forewarning of the 9-11 attack by at least four allied intelligence agencies (France, Israel, Germany, Russia). The Mossad sent a delegation to the CIA in Langley (as per Janes Intelligence Weekly) and told them that an attack using airliners would be mounted within several weeks by Al Qaida, involving about 200 operatives, and run by Amad Mugniyeh (Marine barracks bonber) and Ayman Al-Zawahiri (assasination of Sadat), who are bin Laden lieutenants.
Was the lack of response terminal incompetence or complicity?
terminal incompetence: The Peter Princible in it's glory -- not only do people rise to their level of incompetence, but it is the nature of non-profits (and the biggest non-profit of all being the US Government) to
prefer management by the incompetent. (Excepting at some point, for a short period, in war or disaster.) Only the incompetent can possibly meet the fundamental mission statement of non-profits -- that being NOT to make a profit.
Further, the arts of bribery and graft, as apexed by Team Clinton, are easily practised among the incompetent, and the desire to practise such arts adds considerably to the promotion of incompetence. One by direct promotion, and two by demoralizng and throwing off the competent.