Do you live in a border state? Are mojados being brought across a river and overland to your state by los carteles onto private as well as public land?
Nobody who has any sense will go around landmining the border or strafing mojados with 50 cal guns-the legal/human rights issues would be a losing proposition, since much/most of that land is privately owned-there are people who depend on the ranches and farms they own and operate to make a living, and you can’t put them in danger, stepping over landmines and dodging 50 cal rounds as they go about their normal workday-they also take down and deal with any mojados they catch on their land all by themselves. So your suggestion makes no sense-best to keep all remedies nice and legal unless there is a real war...
The invasion will continue until death is the assured outcome of the effort.
The motivation is essentially infinite.
Are we gonna wait for THIS, like Israel did??