Cryptonym: CACTUS
https://www.muckrock.com/news/archives/2017/dec/11/CACTUS/
A little known but extremely important part of the history of domestic surveillance by intelligence agencies is the CACTUS program. CACTUS was a highly classified channel used by agencies like the Central Intelligence Agency and the Federal Bureau of Investigation to transmit information about “the New Left, Black Militants and related matters.” This channel was never disclosed in the Church Committee reports, even when the reports discuss information that was transmitted through CACTUS. A review of the available documents also indicates that the program is older than previous FOIA releases indicate, with one federal judge questioning CIA’s good faith in processing FOIA requests relating to the CACTUS channel when the Agency declared it was “still utilized” in the mid-1980s. According to a memo released to several researchers, “the CACTUS indicator” was described for FBI Director J. Edgar Hoover by CIA Director Richard Helms on April 22nd, 1970. The conclusion by the very few resources to mention the program has been that the program was first introduced on this date. Director CIA to Director FBI April 22, 1970 SUBJECT: USE OF THE CACTUS INDICATOR The cryptonym CACTUS has been assigned as a teletype action indicator covering teletype communications between this Agency and your Bureau dealing with the New Left, Black Militants and related matters. Use of this indicator will facilitate prompt and effective action on such communications by this Agency. A formerly SECRET message between the FBI and CIA Directors shows that the program predates this memo. The message, dated April 18th, 1970, shows that CIA was sending information about Vietnam War protesters to FBI several days before Hoover had the cryptonym explained to him. It’s likely that the explanation was offered in response to a query from Hoover, who apparently was seeing the cryptonym for the first time. Whether the program was new, or simply new to Hoover, isn’t currently clear.
104-10063-10019: SIGMUND EISENSCHER, CPUSA
Nov. 1970 memo about Michael Eisenscher. See note at the end "Please transmit reply via CACTUS channel."