This document defines espionage and counterespionage. Espionage involves the collection of intelligence against unfriendly countries through both legal and illegal means. Legal espionage can occur through embassies, refugees, infiltrators, or technology. Illegal espionage includes activities like photography of restricted areas, bugging parties, using agents, phone tapping, and electronic surveillance. Counterespionage aims to foil enemy espionage and subversion attempts through preventive measures like controlling identities, communications, activities, movements, and publications to detect subversive activities. Detective counterespionage measures include surveillance, observation, secret searches, and secret inquiries.