Well; you guys can believe what you want about UFO's. In Vietnam, I was in the thick of air traffic observations, working with air to ground support. We kept an official USAF ledger of our Fighter Pilots who were confronted with aircraft they couldn't identify. I was there in '68', and this ledger was continuing from 1965, and believe me, it was full. These reports were from USMarine and USAF F4 Fighter Pilots. By the way, in school they are taught to identify any aircraft in this known world from a distance no larger than a fly.
Pilots were not allowed to fire upon said UFO's. Pilots rotated every so many months, so it wasn't just some wierd experience with just a few men. These men were the top of the crop, the best the world could put up in the skies, and they were seeing something they weren't allow to discuss.
A typical report { under mandatory specific official guidelines } "UFO with revolving red and green lights, does not respond to radio contact. "
Some pilots stated the UFO's would pull out ahead of them, and flat outrun them then turn a sharp 90 degrees and were gone.
But other than that, they couldn't tell us much over the radio, lest they would be removed from flight status. Most generally, only one UFO would be seen on a mission. The only noticeable increase would be when our boys on the ground were in a terrific battle, and the sky was full of air support, then more UFO's would be seen.
That's just what I witnessed during my duty in VietNam. I asked my CO's what they thought, and they wouldn't give me an answer, other than showing me a pictorial book of all the aircraft this world had. I just had to convince myself that God has everything under control and I shouldn't worry about it.