The way to do it - which incidentally is the most difficult, because, you know (as you mentioned) CIA, et al - is to freeze bank accounts. But that would mean major US banks as well, so there's potential blow-back to the US economy.
It really is a bit of an intractable situation, because the entirety of the MX economy is based on low tech, subsistence farming. Drug cultivation earns a premium, which provides a bit more cash cushion for both growers, and a key source of foreign exchange for the banks.
If Trump attacked via financial/banking mechanisms, the economic heart attack that resulting in MX would send millions of refugees north to the USA. If Trump attacked militarily, he has two additional problems in addition to the economic hit: civilian collateral damage (don't think the cartels would start executing peasants and blame it on the US, you know, like the old "wedding" attacks?); and of course an affront to MX patriotism.
The only way to do this right is to help advance the MX economy to the point where it wouldn't have to be dependent on growing drugs. That is, more money could be made in new segments rather than traditional subsistence drug crops. So, what industry would that be in a world where low IQ, lazy Mexicans could compete? Hi tech? LOL Autos? LOL Garment trade? LOL
Think people, think! What does MX have that is the envy of the rest of the world? That's right, real estate. But what is preventing the largest real estate land boom in the history of the world from occurring? Prohibitive MX rules, including restrictions by non MX citizens to own coastal real estate.
So, here's the deal (hopefully Trump people are reading this): you need to offer a carrot along with a stick. The stick is freezing bank accounts and going fully medieval on the cartels and entrenched gov't operatives. The carrot is to open MX real estate up to the billions of Americans, Euros, Indians, Chinese, Japanese and MENA that would literally flood the countries beaches and beautiful mountain regions with development projects the size/scope never seen before.
The issue of drug producing crops in Mexico may not be unsolvable. Coca is not grown in Mexico, and the price of heroin has dropped dramatically in part because of fentanyl taking it’s place. I’m sure the remaining poppy fields would be easy to identify and target.