Scatter the army, hoard food. You might find a few tanks in this acre of grass, maybe a jet resting on that highway running through a remote city in southwest China. You can't destroy the food supply entirely, with some cereal boxes in a bunker under this tree in the forest. You can't kill us all, giant cities of us might be living in a remote forest in the Northwest Territory. We may even have underground cities you don't know about. If you are here peacefully, then good. If you are here to come by force, well, good luck with that.what is this?
Or that is what I would do.