Espionage

Espionage is the covert gathering of secret information, especially by one state or organization about another. It uses agents, technical surveillance, or other clandestine methods.

Human intelligence: Intelligence gathered from people, including agents, informants, and interviews. Espionage often depends on recruiting people with access to protected information.
Sun Tzu: An ancient Chinese military strategist traditionally credited with writing The Art of War. His account of spies made intelligence collection a formal part of strategic thought.
Oleg Penkovsky: A Soviet military intelligence officer who secretly supplied information to British and American intelligence during the Cold War. His reporting provided Western governments with insight into Soviet military capabilities.
Military intelligence: The collection and analysis of information about foreign armed forces, capabilities, and intentions. States use espionage to assess adversaries' forces and plans.
Cuban Missile Crisis: A 1962 confrontation between the United States and the Soviet Union over Soviet nuclear missiles in Cuba. Aerial reconnaissance supplied evidence that shaped decisions during the crisis.
Signals intelligence: Intelligence derived from intercepted communications and other electronic signals. Electronic interception can reveal secrets without placing an agent inside an organization.
The Art of War: An ancient Chinese military treatise attributed to Sun Tzu, including a chapter on espionage. Its taxonomy of spies is among the earliest influential discussions of organized espionage.
Kim Philby: A British intelligence officer who secretly worked for the Soviet Union. His case exposed how ideological commitment and institutional access could compromise an intelligence service.
Industrial espionage: The covert acquisition of trade secrets or confidential business information for commercial advantage. It applies espionage methods to competition among companies or economic actors.
Venona project: A U.S.-British effort to decrypt Soviet intelligence communications, begun during World War II. Its findings exposed some Soviet espionage networks and affected postwar politics.

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