Project SHAMROCK

Project SHAMROCK, considered to be the sister project for Project MINARET, was an espionage exercise, started in August 1945 that involved the accumulation of all telegraphic data entering into or exiting from the United States. The Armed Forces Security Agency (AFSA) and its successor NSA were given direct access to daily microfilm copies of all incoming, outgoing, and transiting telegrams via the Western Union and its associates RCA and ITT. NSA did the operational interception, and, if information that would be of interest to other intelligence agencies was found, the material was passed to them. "Intercepted messages were disseminated to the FBI, CIA, Secret Service, Bureau of Narcotics and Dangerous Drugs (BNDD), and the Department of Defense." No court authorized the operation and there were no warrants.

The precursor to the project according to Budiansky occurred in 1940, "In January 1940 the Army's adjutant general sent a letter to the president of RCA, David Sarnoff, asking if a Lieutenant Earle F. Cook might be assigned to the company..." Cook photographed all international commercial cablegrams. "The clandestine arrangement—almost certainly illegal—set a precedent..." Official wartime censorship began in Dec. 1940, when all cables were "turned over to the government for inspection." According to Tordella, "the collection program 'just ran on' ever since its beginning in World War II 'without a great deal of attention from anyone'..." Three major cable companies provided copies of all international telegrams passing through New York, Washington, and San Francisco. In the 1950s, "New Shamrock" tapped the links of 60–70 foreign embassies.

...
Wikipedia