Is going after the supply a winning battle? I'd say it isn't. All the bases from every drug (except meth I think) come from plants. Plants are nearly impossible to eradicate. The south can't get rid of the Kudzu plant that was introduced from Japan in the early 20th century, and this is a plant that people are trying to eradicate that doesn't have a demand and that isn't being grown clandestinely and guarded by men with automatic weapons. Hell, my parents have been battling crabgrass for an eternity it seems in their yard.
Now from certain areas you can eliminate or greatly reduce the supply of something. Turkey was a prime growing area for illicit opium in the 70s but isn't anymore (interestingly enough, they are a prime area for licit opium used for, heh, "medication"). But opium production didn't just go away, it just got moved to Afghanistan. Then the Tailban put a "stop" to that in 2000, but they also had a ton of reserves in place so they were able to control and limit the supply and increase their profits (much like if someone hoarded Tickle Me Elmo dolls 10 years ago before Christmas would have made a killing on ebay). Eventually another country would have replaced that supply but the Taliban was booted out a year later and the Afghans just continued.
I know I'm not an economic genius, but I do know one thing. If there is a large enough demand for something and that product is not super duper rare (like enriched uranium) and easy to produce, there will be a demand for it. Reducing demand is the only way for it to stop, much like how cigarette sales have declined in this country despite them being totally legal.
