Legalisation is the only sensible way to fight drug related crime of any kind, including the funding of terrorists and war lords. The "War on Drugs" has failed and it will fail in the future. As long as there is an inelastic demand for drugs or any other good, prohibition only creates way more problems than it could ever solve. There should be a regulation on hard drugs (like on potentially harmful medicine) but they should not be illegal either. When people really want to fuck up their life, you can't help them anyway.