When they get serious about taking us out, they won’t send people... they’ll send drones. Good luck with that.
They don’t have enough drones, today, to do that. 10 or 20 years maybe. It’s gonna take alot of drones to take on 300 million people unless they’re planning to drop nukes.
Drones have to be fueled and armed, they have to take off and land, and they have to be piloted, which means they can be hijacked. Not to mention the bases they are flying out of can be taken over. The whole drone thing works great till they are turned against you.