Developed Nations across the world such as Israel use lethal Force to defend their borders from drug cartels, human traffickers, and otherwise ill intentioned people who can't get in legally. There's no reason we can't.

It's a little tougher because the illegal migrant groups crossing the US borders are "families" of 24 men and 3 children, and our government is full of traitors. Even moving the children to their own cells until you can identify who they belong to gets AOC crying at the gates.