Folks are talking about this and I want to throw my two cents in. Sure, we would initially blow away the cartel's armored vehicles and heavy weapons, but the initial success would be fleeting. There are a million reasons for this, but here's a quick summary:
- The cartels would hole up in rough terrain, just like Pancho Villa's forces did in the early 20th century. Sure, we have helicopters which mitigates the lack of roads but the last two decades in Afghanistan do not give confidence in quick military success in mountainous regions.
- The Pancho Villa expedition in 1916 was called off because the Mexican military intervened to oppose American intervention. Most Americans don't really realize just how viscerally Mexicans would react to US forces on their soil in numbers.
- Since the cartels have bought off most Mexican politicians ("silver or lead" - take the payoff or a bullet) the last point becomes even more relevant.
So it's not a question of whether we'd inflict a lot of damage on the cartels. Of course we would. But ultimately we'd leave with our tails between our legs and this would make the situation worse than it is today.
And don't think that we would be safe, north of the Rio Grande. The size of the drug market is unknown but RAND says that just the US black market for drugs was over $100B in 2010. Add in the EU, Asia, the Anglosphere, and South America and this is certainly half a trillion dollars a year. That's a lot of money. The cartels have used this to purchase heavy weapons and armored vehicles, submarines and airplanes. But that isn't where the threat ends.
Consider how much computer hacking $50M or so could buy. We know that the power grid is already compromised - the hope is that it is by nation state actors. But what if it is Black Hats for hire? It's entirely plausible that if the cartels face a truly existential threat from the US military that they could take down big parts of our critical cyber infrastructure. This threat has been pretty clear for a decade; I've been beating this drum for that long, although I've mostly given up by now since it's getting worse not better. Someone in the cartels will have noticed this.
And so while the idea of "let's go blow the cartels away" sounds good on the surface, it's an enormously bad idea. We'd be fighting a 3rd generation war while the cartels would escalate to a 4th generation one - and we are entirely unprepared for this.
I'm at an all day meeting, so more thoughts on just how fragile our cyber infrastructure is will have to wait. But it's not just bad, it's worse than you can possibly imagine.
You want to hurt the cartels, then you dry up the cash flow. You end the war on drugs, legalize everything, and give the drugs away for free. They can't compete with free. Anything short of this and you're just going to get a lot of people killed and end up right back where you started.