The operation was officially sanctioned in 1953, was reduced in scope in 1964, further curtailed in 1967, and recorded to be halted in 1973. There remains controversy over whether this operation ever ended, or continues presently. The program engaged in many illegal activities, including the use of U.S. and Canadian citizens as its unwitting test subjects, which led to controversy regarding its legitimacy. MKUltra used numerous methods to manipulate people's mental states and alter brain functions, including the surreptitious administration of drugs (especially LSD) and other chemicals, hypnosis, sensory deprivation, isolation, verbal and sexual abuse, and other forms of torture.
