I'm trying to come up with a concept that will unify the ideas upon which the Mexican invasion and subsequent occupation of the American Southwest are predicated on. Here's what I've come up with.
Suppositions:
- In a alternate timeline (v1.0 is the way to go, IMHO), NAFTA doesn't happen, or if it does, in a somewhat modified format.
- Oil markets are bullish and Mexico receives an influx of petro-dollars.
- Mexico has to deal with a resurgent insurgency in its southern states. Fairly or not, Guatemala is accused of collusion with the guerillas.
Ergo:
There is a minor trade dispute with the U.S. Not enough for either nation to feel threatened by the other, but enough to make them both grumpy with one another.
Instead of taking a progressive approach, spending those petro-dollars on building badly-needed infrastructure and helping the impoverished peasants that support the rebels, the Mexican government, succumbing to pressure from its military establishment, decides to spend the money on armaments instead, so that it can finally "pacify" the restive southern states.
Because of the trade dispute with the U.S., Mexico conscientiously decides not to buy American. But because of American diplomatic clout, they can't buy current generation armor (and the Mexican government isn't foolhardy enough to try to buy Soviet). So, they look to buy used from non-aligned nations. France is upgrading its MBT fleet from the AMX-30 to the Leclerc, so Mexico approaches the French to buy retired AMX-30s. The French aren't necessarily non-aligned, but they always try to do their own thing, so they agree to sell the Mexicans a regiment's worth of AMX-30s, and to throw in a bunch of retired AMX-13s as well. A deal is struck.
OR
Mexico and Argentina broker a deal for the former to purchase a fleet of new-build TAM tanks from the latter, and Argentina offers to throw in its upgraded Shermans to sweeten the deal.
AND (regardless of which of the two above alternatives you select)
In the meantime, Mexico looks into upgrading its existing armor force. It makes a deal with Brazil for the latter to upgrade its fleet of M3 Stuarts to the X1 status. Brazil offers to sell some of its own upgraded fleet of X1A-2s to Mexico as well. A preliminary agreement to buy some Brazilian EE-11 Urutus and EE-9 Cascavels is reached as well.
This unified theory explains some of the tension between Mexico and the U.S. and justifies/explains Mexico's acquisition of non-American AFVs in the run up to the invasion.