The FBI loves its counterterrorism work. Loves it so much, it‘s pretty much abandoned all pretense of being a law enforcement agency. It acts as though it‘s somewhere between the NSA and the ATF: interested mostly in picking through surveillance dragnets and running sting operations that turn people who have trouble with basic skills like holding down jobs into national security threats.

But it can‘t score anti-terrorism goals on unguarded nets without a crew of informants. It works with immigration authorities to coerce visiting foreigners into providing the agency with intel. It goes further than that, though. It also operates a witness protection program for informants/witnesses actually involved in actual terrorist activity.