The miltary has weapons that can already do stuff like this, but it has been gossiped about that these beings could have psychic powers, or some kind of technology that can do things like make us see what they want us to see, like them looking like a human or a bird.

Alot of these ancient stories talk about shapeshifters, even in the bible you see alot of angels disguising themselves, the same with the greek epics where the gods would take different forms.