Background

Sidney Gottlieb approved of an MKUltra sub-project on LSD in this June 9, 1953, letter.

The project's intentionally obscure CIA cryptonym is made up of the digraph MK, meaning that the project was sponsored by the agency's Technical Services Staff, followed by the word Ultra which had previously been used to designate the most secret classification of World War II intelligence. Other related cryptonyms include Project MKNAOMI and Project MKDELTA.