The FBI and CIA knew beforehand that majot terrorist attacks were going to occur.
1) an attack on the WTC
2) anthrax in the US mail
3) Cyber atacks on banking

From Al Martin's website there was this:

Apparently CNN has had the same documents the FBI had but they wouldn't release them to the public either. These documents, seized from one of bin Laden's people a few years ago in New York, discussed a major operation being planned. The first leg was the attack itself. The second leg would be the use of anthrax to disrupt the US postal system. The third leg was to be a major cyber-attack against the US banking system, disrupting banking and shutting down ATMs.