The Pentagon has plans to deal with a hostile alien space invasion. The Pentagon is set to react.
How likely is it that an alien invasion will target us for extermination? Why is it we always think the worst will happen? Why do we assume we'll be blasted to bits by superior alien firepower?
The universe is billions of years older than the earth. That means that other planets with intelligent life on them could be older than earth and more advanced that we are. They might have weapons we can't even conceive of. How does the Pentagon plan for that?
It's unlikely that visitors from outer space would be hostile. If they're advanced enough to buzz around in outer space then that means they're more than likely to have also evolved into a civilization that has eliminated war, suffering, and conflict.
Planets capable of supporting life may never have evolved beyond the microbial stage. Others may have given rise to intelligent life. That intelligence could be millions of years ahead of us which means that if they did come and take a look at earth and its inhabitants, they might just ignore us because we're just too primitive to fuss with.
The United Nations advises that if aliens do send us a radio signal that we are not to reply until an international council can be convened to decide what to do. The reason for this is that we don't know if they're peaceful aliens or hostile invaders. We don't want to set ourselves up for an attack.
It's unlikely these visitors from other worlds would look like us. They developed from the unique conditions of their home world just as we did from ours. They evolved from a different mix of chemicals and circumstances. Intelligent life on a world of water would be far different than a planet with land mass on it.
As to UFO's, 95% have been explained. Only 5% haven't. It's that 5% that astrophysicists are interested in. The 5% that can't be explained away by our science. Not yet anyway.
If aliens needed water or other resources from earth, there are plenty of planets out there that are just like ours that are uninhabited. They would likely obtain what they needed from those planets without disturbing the ones with life on them.
Life is out there someplace. We keep sending out radio signals but get nothing back. The day we do, we have a decision to make. Do we respond to it or keep our mouths shut. Do we risk contact or consider the consequences?
I guess we'll see when that happens because as many scientists agree, one day it will.