Using the military is useless unless you are willing to shoot these invaders.
Not that I have anything against shooting invaders.
This will not stop until Congress passes a law giving the US government an absolute right to repel and or return anyone entering the US from Mexico or Canada, with no right of appeal or right to claim asylum. The President will have to defy the inevitable injunction granted by a Democrat judge from Hawaii, and make it clear that the border is absolutely closed to all invaders.
You don’t have to shoot them, just make temporary camp to process and return them. They can build them themselves.
It’s good to keep in mind that the invading army is (of course) almost entirely men of military age. If you have to shoot someone, that’s the best kind of target. If they can find any women and children, they might push them to the front lines, but I think they have few of these.
To defend our nation? Seems like we've let a whole lot of people be shot, all over the globe, to further the globalization agenda of The (not so) Invisible Hand.
Ok, so shoot them. This is war.