MK-Ultra was the Super Top-Secret CIA operation where they studied all forms of "unconventional warfare" including, but not limited to:

Mass hypnosis
Chemical Warfare
Drug Warfare
Propoganda Techniques
and possibly even experiments with some of Nikola Tesla's waves.

MK-Ultra is most well-known because there was a part of it that dealt specifically with LSD. That branch was supposedly shut down because it wasn't safe to do anything around the people in that branch because they habitually snuck LSD into people's drinks, foods, and even on their skin (LSD is active through the skin, too).

Though that's true, I think MK-Ultra is what eventually led the government to ban LSD and other psychedelics.

The LSD branch probably concluded that people under the influence of LSD cannot be controlled at all. They will do what they want when they want to, and nothing anyone tells them will change that (under the influence). So...bye bye psychedelics.