Trump and other drug warriors refuse to face the reality that as long as the United States retains a policy of drug prohibition, violence in Mexico likely will get worse, not better. Americans spend an estimated $146 billion annually on currently illegal drugs, according to a recent RAND Corporation study, and Mexico is an especially important supplier. Rival cartels vie with each other to control the lucrative trafficking routes into the United States, using any means necessary.
https://www.cato.org/blog/trump-wants-escalate-already-disastrous-drug-war-mexico
