Correct me if I’m wrong but don’t we have the NSA, CIA, DIA and all branches of the military for national security?

From Foreign Policy:

The FBI’s creeping advance into the world of counterterrorism is nothing new. But quietly and without notice, the agency has finally decided to make it official in one of its organizational fact sheets. Instead of declaring “law enforcement” as its “primary function,” as it has for years, the FBI fact sheet now lists “national security” as its chief mission. The changes largely reflect the FBI reforms put in place after September 11, 2001, which some have criticized for de-prioritizing law enforcement activities. Regardless, with the 9/11 attacks more than a decade in the past, the timing of the edits is baffling some FBI-watchers.