At least since World War I (remember the "Zimmermann telegram"?), the enemies of the United States have tried to gain Mexico's cooperation in a joint strategy against the United States. The incentive offered has always been the "restoration" of lands in the American Southwest that many, if not most, Mexicans still consider legitimately part of Mexico. The Chinese are very much aware of this, especially the continuing historical enmity between the US and Mexico over the 1846-48 war. Let's not kid ourselves: our border with Mexico is now, and will increasingly be in the future, a source of threats to our national security, aided and abetted by deep rooted Mexican popular hostility towards the US, and China has exploited and will increasingly exploit our vulnerability on our southern border. Depend on it.
Yes, I can see this happening. I've always thought lawn care services were just a cover for political insurgency groups (PIG). Of course the can be no disputing the goal of the radical outfit Calixo Amarrillo y Beaumont Revolutionary Indian Takeover Operations (CABRITO). Speaking of which, has anyone else noticed now at Taco Bell you have to ask for hot sauce or they won't give you any?
Note that in each case that it's been tried, the Mexican elites have not taken them up on the offer. There are several reasons for this. The biggest one now is that grabing the Southwestern US gets all those folks they worked so hard to chase OUT of Mexico back IN.
If there ever is a nuclear strike on the US, Mexico will probably have a really severe problem with illegal immigration from the US.