NSA is DoD systems, DHS is other governmental systems and some critical private sector systems, FBI is counterintelligence investigations. They all overlap and help each other.
NSA is under Intelligence Community[0]. I think Defense Intelligence Agency is DOD's intelligence branch.[1] But my own wiki link is saying both NSA and DIA don't have parent agencies so idk..
Both the NSA and the DIA are under the DoD. Both are intelligence agencies and are part of the IC. All of the IC members fall under the Director of National Intelligence (DNI). The NSA and DIA differ in their missions. The NSA is primarily focused on Signal Intelligence (SIGINT) whereas the DIA is focused on Human Intelligence (HUMINT), mostly pertaining to foreign militaries.
