Correct. There is a strong dividing line between those two organizations, resulting from some very bad misbehavior by the FBI and CIA in the 1950s and 60s. The Foreign Intelligence Surveillance Act was set up to allow some agencies to collect information on non-Americans using techniques they'd never allow on citizens, while other agencies can use a more restricted set of techniques on Americans.
After 9/11 they breached that somewhat, because of a (not entirely well-founded) belief that the separation kept them from preventing the attack.
Those are the two ends of the spectrum being debated here: harassing Martin Luther King on the one side, and 9/11 on the other. No compromise is going to make everybody happy. In fact, no matter what, it's going to make everybody mad.
How is 9/11 on the other side of harassing MLK? FBI had been told before 9/11 about non-citizens paying with cash at flights schools for heavy aircraft simulator time.
After 9/11 they breached that somewhat, because of a (not entirely well-founded) belief that the separation kept them from preventing the attack.
Those are the two ends of the spectrum being debated here: harassing Martin Luther King on the one side, and 9/11 on the other. No compromise is going to make everybody happy. In fact, no matter what, it's going to make everybody mad.