I've read somewhere that you must have a certain chemical to make I think cocaine. There are only 3 companies in the entire world that make this particular chemical. Two are in the US and one is in Germany and 90% of their product is shipped to Colombian companies. Well, if you wanted to shut it down, we can easily get with Germany and have these three companies shut down the shipments to Columbia of these chemicals. Cocaine would get so high no one would be able to buy it. However, one can break addiction to cocaine.
Marijuana on the other hand can be grown almost anywhere. It is impossible to stop it. It is like alcohol, not stopping the consumption. Legalise it and tax it. Same people would still use it. One can break addiction to MJ.
Heroin is made from poppies. Poppie fields can be found and sprayed with Round up or agent orange. Heroin dries up. Also, if you find a heroin addict, lock them in a padded cell like they did or do in Japan, and make them get off of it cold turkey. No more heroin addict. Also, one can break addiction to this drug also.
Methamphedimenes, are the most dangerous, and once addicted, can never get off the addiction. This should always be illegal.
So, legalise some, tax it, but not others.