If Mexico wants to deter America, their best bet by far is to pose a credible insurgency threat. And in that regard, between the number of Mexican nationals and sympathizers in America, the number of guns in Mexico, the national pride of the Mexican people, and their established proficiency with asymmetric warfare (at least from their cartel elements)... I think they've got their bases well covered. Mexicans have the capacity to make an invasion of Mexico be extremely painful to the American public.

But Mexico using conventional military force to deter America? That's completely absurd.

That Mexico has zero tanks or infantry fighting vehicles or real self propelled artillery might tell you how they've felt about the odds of the US actually invading again.

(IMO they should get some of these things even if there's no chance of the US invading, given how much firepower some of the cartels have.)

That's not really something Mexico can reasonably do. They are narco-terrorist state and everything there is heavily intertwined with the cartels. They would not want such a thing to happen. War with the US would be bad for their multi billion dollar business.

I'm ok with you guys taking over. You probably don't want us though.