The conspiracy theory that the CIA was causing drug addiction in the US has a long history. It has often been put forward at various times.
Drugs profits from Afghanistan were used by the CIA to fund the Mujihadeen against the Russians when George Bush was head of the CIA.
Drug running was also tied to the Iran Contra scandal.
When the American pilot Eugene Hasenfus was shot down in Nicaragua there were rumors he was running drugs for the CIA.
Here's some sketchy info on some of the other instances.
http://en.wikipedia.org/wiki/CIA_drug_trafficking
Like all conspiracy theories it has some facts intermingled with a lot of speculation. The CIA was more than willing to work with drug smugglers because they needed sources. The drugs were being sold in poor US communities which often meant black communities. It takes little to turn it into a government plot to addict minorities to keep them down.