Stratfor explains constraints on fighting this set of problems.
Things have come a long way from the time when Mexican officials figured the drug trafficking was an American problem and asked why they should fight our problem when Mexico just reaped the benefit of dollars flowing south to pay for the drugs.
Deals with the Devil rarely work out well, in the end.
UPDATE: How well did ignoring the enforcement of laws that let drugs flow north to America? About this well:
The Mexico's National Human Rights Commission (CNDH) reported today that 99 percent of crimes go unpunished in this country, which shows a very low police efficiency against high rates of violence.
Mexico should be the first country to want America to have effective border controls.