@SmudgeTheInsultCat@mas.to

are there any sources that could backup that claim?

I know that many countries had done such kind of "science" - but it's always good to have valid sources.

Edit:

Some background of the origin: https://www.snopes.com/fact-check/1960s-kgb-experiments-subjects-brainwashed/

Tadaa: "For this reason, we have rated the claim unproven"