I think a slightly more diligent administration (e.g., Al Gore’s) might well have prevented the 9/11 attacks.
As a charter member of the Al Gore Fan Club, I’d love to believe that. But those attacks were the result of decades of bad choices by Americans (especially the national leadership.) If Gore had somehow been prescient enough to eliminate all conflict among the intelligence agencies and cause the FBI administration to eagerly jump on intelligence coming in from the field, maybe, maybe. But it wasn’t George Bush’s policies that caused the attacks. It was U.S. policy since about 1946.
In the UK they are trying to lambast MI5 for the 7/7 tube bombings.
It seems that two of those involved had come to the attention of MI5 and the police as a side effect of spotting five other young lunatics who stored 1300 lbs of Ammonium Nitrate (?) in a storage facility.
The thing is, that until 7/7 we had not had any Moslem extremist bombs, so while given hindsight one could forsee something like 7/7 - until it actually happened it was not clear whether one was dealing with a real threat or a bunch of fantasists.
I would say the same goes for 9/11