They will probably give him the five minute version of Richard Dolan’s three volumes on UFOs and the National Security State.
Let me save Donald some time:
Yes, they exist.
Yes, we have treaties with them.
Yes, both parties have violated the treaties.
Yes, their weapons could turn us into road-kill, and after they killed us many would be happy to eat us.
Welcome to the White House!
The idea of aliens killing us is something we could debate all day.
We have way more to worry about with the invading force that’s already here : Islam.