The attack on America
We didn't have a clue. We regularly speak with various intel types; they didn't have a clue. No one but the planners knew about this; it MIGHT have been possible to forecast this and prevent it, but hindsight is 20-20.
The mountain of intelligence gathered by our government every day is really and truly astounding; it would be physically impossible for it all to be examined by a person competent to understand what it meant within a reasonable period of time.
No blame should be given to the U.S. Intelligence services for dropping the ball on this one.