If nothing else; we are a pragmatic bunch. ;)
I like the mini gun idea but there could be too much collateral damage so maybe fire bombs or flame throwers would be a better choice in this case.
Rifle butts and tear gas.
This is an invasion, they’re announcing their intentions to rush our border and overwhelm our people.
If we’re not prepared to defend our border, we don’t have a Country.
How about a compressed air driven paintball gatling gun/minigun. Fill the paintballs with pepper spray, “infinite stink”, tear gas and other goodies.
Such miniguns already exist for BB’s with impressive performance.
https://www.youtube.com/watch?v=9i-Eht5-JSQ
https://www.youtube.com/watch?v=lmHENtHW9O0