The United States Naval Criminal Investigative Service (NCIS) is the primary investigative law enforcement agency of the U.S. Department of the Navy. Its primary function is to investigate major criminal activities involving the Navy and Marine Corps, though its broad mandate includes national security, counterintelligence, counterterrorism, cyberwarfare, and the protection of U.S. naval assets worldwide. NCIS is the successor organization to the former Naval Investigative Service (NIS), which was established by the Office of Naval Intelligence after the Second World War.

The Federal Law Enforcement Training Centers serves as an interagency law enforcement training body for 105 United States government federal law enforcement agencies. The stated mission of FLETC is to "...train those who protect our homeland". Through the Rural Policing Institute (RPI) and the Office of State and Local Training, it provides tuition-free and low-cost training to state, local, campus and tribal law enforcement agencies.