That has always been the FBI's job, really tough to do without Nat'l security intel inputs. If all you get are the products it is impossible to prove a case as you are relying on analysis that isn't LE focused.
Hmm, I see. I was forgetting domestic terrorism by foreign elements. So is the FBI forbidden to do surveillance on, for instance, suspcious mohammedens? Probably I am too much a simpleton to delve any more into this topic, as interesting as it is.