Those of you who think it was the Bush administration who primarily dropped the ball in the lead-up to 9/11 may find this of interest:
A military intelligence team repeatedly contacted the F.B.I. in 2000 to warn about the existence of an American-based terrorist cell that included the ringleader of the Sept. 11 attacks, according to a veteran Army intelligence officer who said he had now decided to risk his career by discussing the information publicly. The officer, Lt. Col. Anthony Shaffer, said military lawyers later blocked the team from sharing any of its information with the F.B.I.
Me, I think the whole thing was probably inevitable simply because we couldn't concieve of it and they could. There will be plenty of blame to be dished out by historians for decades to come.
But those out there who think that blame should suddenly start on January 20th, 2001 and be exclusively (or even primarily) placed on the shoulders of those who took office then need to take a long, slow look at their own biases.