Combating Japanese Espionage with MAGIC

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Combating Japanese Espionage with MAGIC
The use of espionage by the Japanese government against the United States was prevalent just before World War II and immediately following the United States entry into the war. In fact, the intelligence derived from Japanese espionage helped prepare the Japanese military attack on Pearl Harbor on December 7, 1941. However, unbeknownst to Japanese diplomats, the United States was decrypting their communications through a secret program called MAGIC. This program would eventually document the vast espionage activity conducted by the Japanese government.
History of MAGIC
The Cipher Bureau
In May of 1919, the first civilian intelligence agency in the United States was created, called the Cipher Bureau. The Cipher Bureau was headed by the former Chief of the Army cryptographic section of Military Intelligence (MI-8), Herbert O. Yardley. The primary mission of the Cipher Bureau was the decryption of foreign diplomatic communications. Although the Cipher Bureau had many undocumented successes, their most famous success came during the Washington Naval Conference of 1921-1922 (NSA, 2012). The Cipher Bureau was able to decrypt the communications of the Japanese delegation to the conference. This information gave the United States a tangible advantage at the negotiation table against the Japanese, regarding naval limitations. Unfortunately, in 1929 the Cipher Bureau would be decommissioned as the new Secretary of State did not agree with the practice of Communication Intelligence (COMINT) during peacetime. This new Secretary of State, Henry Stimson, would go on to publicly rationalize his decision to close down the Cipher Bureau by saying, "Gentlemen do not read other gentlemen's mail (NSA, 2012)....

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Works Cited

National Counterintelligence Center (NCC). 2010. Chapter 2: Magic. Volume 2: A Counterintelligence Reader – Counterintelligence in World War II.

NSA. 2009. Pearl Harbor Review - Red and Purple. National Security Agency/Central Security Service. http://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/pearl_harbor_review/red_purple.shtml (accessed 26 January 2014).

NSA. 2009. Pearl Harbor Review - Signal Intelligence Service. National Security Agency/Central Security Service. http://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/pearl_harbor_review/sis.shtml (accessed 26 January 2014).

NSA. 2012. Pearl Harbor Review - The Black Chamber. National Security Agency/Central Security Service. http://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/pearl_harbor_review/black_chamber.shtml (accessed 26 January 2014).

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