I’m sure that’s a legitimate scenario, but I think it’s more likely they are here to be some sort of UN or NATO military force.
Doubtful, the UN needs a sponsor for their forces not some illegal alien lash up. There is no way in hell a NATO country would get involved in this. Millions of idiots fighting the US mil would get slaughtered. Additionally any NATO country involved would be expelled from NATO and be barred from trading with the US probably forever. While I think pf the impossibility of it happening, it would guarantee the death of the UN.