They are not making war? I beg to differ, many that pass by me are armed cartel smugglers, dressed in black and carrying significant firepower. Google cartel in U.S. and see where they are already operating within our country. Not to mention the various gang members that make the crips and bloods look like boy scouts. That is an invasion or at least should be.
It should be, and in common nomenclature, it is.
But from my understanding of Constitutional law, it is not one in the federal sense.
That's why it is up to the States to stop this horde of multinational trespassers for exactly the reasons you mentioned.