There is an idea that the CIA helped the Nicaraguan Contras ship cocaine to start the crack epidemic to take weaken black resistance like the Black power movement.
Well, this was not just an idea but a whole investigation that proved to be true by the journalist Gary Webb. He sheds light on this through this interview:
Also, please! Give his book a try if you are interested in this topic because it is a very important one now due to the US trying to invade Venezuela.

