I believe the only 3 real terror attacks that have been prevented since 911 have been prevented by citizen actions and have completely gotten past the government. All other attackers have carried out their plans, so not caught by the government, or the government themselves, such as the CIA and FBI, manipulated individuals into thinking they should carry out a terrorist act so that they could "stop" them. Which btw is ridiculous. Stopping someone from doing something they weren't going to do without that same person convincing them to do it isn't helping anyone.