History of espionage
Spy tunnel in Berlin.
Espionage, as well as other intelligence assessment, has existed since ancient times.
Pre-modern espionage
Early strategists such as Sun Zi stressed the need for military intelligence.
Modern times
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There are several methods for counter-intelligence. Secrecy campaigns were widely applied during the World Wars.
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A tape recorder on display in Moscow.
Further information: History of Soviet espionage and Espionage in World War II
With the Modern Age came the concept of professional police organizations, the police state and geopolitics. New intelligence methods arrived, such as imagery intelligence, signals intelligence, cryptanalysis and spy satellites.
Cold War
Further information: Cold War espionage and Nuclear espionage
Post-Cold War
Further information: War on terror and Electronic warfare
See also
Further reading
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