[lazaroclapp]

I guess I was thinking about a unilateral intervention by a single country's army. UN peacekeepers are a different thing altogether, both the scope of the mission and the goals are usually very different. I don't have enough information to know how would that turn out. Keep in mind that they would be going into a very complex system that includes actors such as: the drug cartels, federal and state police, the Mexican army, federal and state political bodies, (multiple) self-defense civilian armies, (multiple) organized protest movements. The more official of those actors are - to an unknown degree - corrupted/infiltrated/colluded with the cartels. The more unstructured ones might very well consider peacekeeper intervention forcing them to disarm or stopping them from protest acts (which have included burning a state police building, an act that had surprising public support) to be further government repression.

In general I think just having independent media and investigators from outside the country can be helpful, since they can be perceived as not part of the system of internal corruption. I think it gets a lot more complicated when you have international actors as supposed to observers and/or pressure. Not saying it can't work, but it is far from simple to predict... (there are, of course, people who know great many orders of magnitude more about the issues involved than I do, both within and without Mexico, so maybe someone is looking into whether or not that sort of intervention would help).