“ Only if you are in imminent danger of taking someone's life. You must literally have the weapon in hand and pointing it at someone else.”
So if you are behind a tree shooting at IS forces and you run to another tree you can’t be legally shot because you weren’t actively pointing a gun. We have to wait until you get to the next tree to shoot back. Sorry but that’s ridiculous. Enemy combatants do not have broad constitutional protections.
Right they migrated but did not enter illegally. There was no government or law to prohibit them from coming. There were people, but by their own admission they had no concept of ownership of land so nor rules. They held their land by might as all tribal cultures did.