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The Venona project was a counter-intelligence program initiated by the United States Army Signal Intelligence Service (a forerunner of the National Security Agency) that lasted from 1943 to 1980. The program attempted to decrypt messages sent by Soviet Union intelligence agencies, including its foreign intelligence service and military intelligence services.〔Benson 2001, p. 5〕 During the program's four decades, approximately 3,000 messages were at least partially decrypted and translated.〔Benson 2001, p. 7〕 The project produced some of the most important breakthroughs for western counter-intelligence in this period, including the discovery of the Cambridge spy ring〔Benson 2001, p. 34〕 and the exposure of Soviet espionage targeting the Manhattan Project.〔Benson 2001, pp. 20–22. Benson gives a basic list of the relevant messages; other accounts include Haynes and Klehr, p. 304, and West, p. 197.〕 The project was one of the most sensitive secrets of United States intelligence. It remained secret for over a decade after it ended and was not officially declassified until 1995. ==Background== During the initial years of the Cold War, the Venona project was a source of information on Soviet intelligence-gathering activity that was directed at the Western military powers. Although unknown to the public, and even to Presidents Franklin D. Roosevelt and Harry S. Truman, these programs were of importance concerning crucial events of the early Cold War. These included the Julius and Ethel Rosenberg spying case and the defections of Donald Maclean and Guy Burgess to the Soviet Union. Most decipherable messages were transmitted and intercepted between 1942 and 1945. Sometime in 1945, the existence of the Venona program was revealed to the Soviet Union by the NKVD agent and United States Army SIGINT analyst and cryptologist Bill Weisband.〔 〕 These messages were slowly and gradually decrypted beginning in 1946 and continuing (many times at a low-level of effort in the latter years) through 1980, when the Venona program was terminated, and the remaining amount of effort that was being spent on it was moved to more important projects. To what extent the various individuals were involved with Soviet intelligence is a topic of dispute. While a number of academics and historians assert that most of the individuals mentioned in the Venona decrypts were most likely either clandestine assets and/or contacts of Soviet intelligence agents,〔''"How VENONA was Declassified"'', Robert L. Benson, Symposium of Cryptologic History; October 27, 2005.〕〔"Tangled Treason", Sam Tanenhaus, ''The New Republic'', 1999.〕 others argue that many of those people probably had no malicious intentions and committed no crimes.〔〔Tales from decrypts. ''The Nation'', 28 October 1996, pp. 5–6.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Venona project」の詳細全文を読む スポンサード リンク
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