Who would deal with an alien invasion

Just research for a book, I know there are countermeasures and stuff in place. I've heard people talk about it but who would it be. FBI, CIA, DOD ?

Border Patrol?

Any race capable of crossing interstellar space with enough force to overwhelm is going to able to deal with humans with little or no effort, for example they could drop a number of bio engineered viruses into the atmosphere, or if they are willing to wait, drop a few very large rocks. In effect any plan is totally futile. A negotiated surrender would be out best chance of survival.

Hi
by the time they react it would all be over, we would find we where over run.
what ever nonsense you may think up. here is the logic they have travel led further than we could even think of , for a start. so how can it end in a peaceful way unless they are friendly and they would stay well clear of any agencies. if the past has been anything to go by.
with invasions like pearl harbour, they would be here and our defence mechanisms would be useless against such any alien.

I've often thought that the best people to deal with visiting aliens would be young children. They are honest and forthright because they haven't yet learned how to lie, cheat, and deceive.

Military, probably starting with airforce secretly before public knows, then would continue on ground

the military

We need everyone, cause the aliens would be way more advanced than us if they reach us now.

Making friends with them would be ideal

some facts about floating diamonds in space: the diamond planet
http://floating-diamonds.blogspot.com

UGH!! YOUR ALWAYS HARASSING ME

WHY DO I HAVE TO PUT UP WITH IGNORANCE!!!!????!!!

UGH!!.....IM GONNA SNAP!!!!!

NYFB None of your ******* Business