Outermost defense zone which typically does not have boundaries.
Explain warning zone
Security forces must classify contacts in the warning zone as either threats or non-threat. Classification measures and warning zone parameters are based on specific threats.
Explain threat zone
Innermost layer of defense. All personnel, vehicles and vessels must be classified as threat or non-threat before interning zone. To neutralize threats, the threat zone must be organized to bring maximum destructive fire.