Saber Rattling - Doubling Down

would Mexico encourage or fight against the US?

I'll make it simple for you Nic - there is NO chance the Mexican public, or its government, would support an incursion/invasion/support action by the US military. I think they are all too well aware of how noble US intentions can quickly backslide into pure self-interest, to the detriment and misery of the locals. Examples abound.

Well, at least the U.S. could say, "Hey, there's a precedent here. We've invaded 10 other times, right?"

175 Years of Border Invasions: The Anniversary of the U.S. War on Mexico