They find mentally unstable people and use undercover agents to convince these people to commit acts of terror, often even giving them the tools to succeed... And then they swoop in to stop the attack and yell to the media "SEE WE SAVED THE DAY AND STOPPED TERRORISM!!" Nevermind that this person would have never been in this position without the FBI's backing. It's a lot easier than stopping real terrorism and gets them the budgets they want.

I mean COINTELPRO, the villification of black panthers, the railroading of Bruce Ivins in the anthrax attacks...

You must be living under a rock if you think the FBI is any better.

EDIT: made links inline instead of separated.