Bring it on, oh, mighty warrior.
The US has had border skirmishes with Mexico before, and Mexico did not fare well.
Federal troops of the United States cannot exercise their combat duties on any of the states of the United States, because of something called the Posse Comitatus act, that is what National Guard (the state militias) are for. But they can operate freely on foreign soil, and as I recollect, Mexico is foreign soil.
Don’t open up on this “reconquista”, it may go very badly for Mexico.
What people are failing to realize is the fact that Mexico is trying to emulate the conflict in Israel with the palestinkians. They, being Mexico, have been promoting and assisting people to emigrate into southwestern United States for the eventual overthrow of those states to take them back. Some say this nothing but conspiracist propaganda but its happening in front of our eyes like the Islamic invasion into Europe. Mexico is taking their sweet time. Mexico wants the southwestern portion of the United States because they claim it was theirs initially. And like the idiots on the left they are allowing them to do it. While we have had issues with Mexico before, we, the USA, have not always won in those wars. However, due to the dilapidated state Mexico has become, they could no longer very much harm nor could they hold territory for very long should they choose to go to war. That is of course the left doesn’t interfere and give it to them. People in the states would be hurt and even killed initially but once we responded Mexico would not have a chance.