A little known, but extremely important, part of the history of COINTELPRO and abuses of the intelligence agencies is the CACTUS cryptonym/program. CACTUS was a highly classified channel used by CIA and FBI 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 the CACTUS channel. A review of the available documents also indicates that the program is older than previous FOIA releases might indicate.
According to a memo released to several researchers, the CACTUS indicator was described for FBI Director Hoover by CIA Director Helms on April 22, 1970. The conclusion by the very few resources to mention the program has been that the program was first introduced on this date.
https://glomardisclosure.com/2017/03/12/the-cactus-documents-show-cia-aided-fbis-cointelpro-even-after-it-ended/