My brother spent 20+ years in the Air Force in an area that put him in contact with classified info, aerial/satellite reconnaissance, etc. He's a hardcore patriot and I've never known him to lie.

He recently told me the following:

The US (and probably other countries) have been visited by what he called 'extraterrestrial drones' at many of their nuclear weapons installations since WWII. They don't think the crafts are piloted by beings of any kind and they have absolutely no idea where they are from.

Though I have a hard time wrapping my head around the idea, I did believe what he told me.