Policing or "internal" intelligence agencies most commonly deal with a country's internal intelligence needs, including (but not limited to) those regarding national security.

Threats are assessed and processed in much the same manner as is used by the military. Commonly encountered scenarios include counter-terrorism, computer intrusions, surveillance, weapons of mass destruction, white-collar crime, and training programs. Officers must be equipped and trained to handle these and a wide array of other situations.

These kids are fun. FBI. DEA. MSS. KAPO. MI-5. They rub shoulders with the above and below groups, mingling via inter-office liasons and the like. Sometimes they themselves will cross the line. For example, the Chinese Ministry of State Security is one part police force, one part counterterrorism unit, and one part elite military regiment. Some police intelligence units are even more powerful than their military counterparts.

Take care and tread softly. If you aren't a member of the team, these guys can be dangerous.

—I, Spy