An excerpt of an interview given by former astronaut Gordon Cooper - Mercury 9, Gemini 5 - to OMNI Magazine in 1980, where he is asked about astronaut sightings of UFOs and about his own UFO sighting when he was an Air Force pilot in Germany in the 1950s.
Excerpt of interview with Gordon Cooper: OMNI, March 1980, p. 106
OMNI: What about the repeated allegations that the astronauts saw many UFOs?
COOPER: It got so bad that there were deliberately falsified tapes of communications with the astronauts, where UFO material was simply edited in. To my knowledge, the only astronaut on any of the Mercury, Gemini, or Apollo missions who ever saw anything that might have been a UFO was Jim McDivitt, but he didn't get enough pictures to prove anything substantial. That's the only case, in spite of all the stories you hear.
OMNI: Didn't you go after some UFOs as an air force pilot in Germany in the 1950s?
COOPER: Yes, several days in a row we sighted groups of metallic, saucer-shaped vehicles at great altitudes over the base, and we tried to get close to them, but they were able to change direction faster than our fighters. I do believe UFOs exists and that the truly unexplained ones are from some other technologically advanced civilization. From my association with aircraft and spacecraft, I think I have a pretty good idea of what everyone on this planet has and their performance capabilities, and I'm sure some of the UFOs at least are not from anywhere on Earth.
OMNI: Aren't you concerned about the reaction of people who may read this?
COOPER: I've always been honest about my views on this subject. Because the astronauts have been so badly misquoted by irresponsible journalists, it's up to each of us to say what he believes in. I'm engaged in a lawsuit against people who used my name for a commercial venture, quoting me to the effect that I'm dedicated to forcing the government to tell the truth about UFOs. I never said that at all. If any UFO information is being suppressed, it's certainly not in the U.S. Air Force, because I was at a high enough level to know about it.
In defense of the military attitude, I can't really blame them for being negative when I consider ridiculous things that have been said and written and the fact that the military is responsible for national security. It's a little embarrassing to acknowledge they can't explain some things.
OMNI: ...Are people psychologically ready to face it if UFOs should prove to be manned by visiting aliens?
COOPER: People want to know what's going on in the world around them, and I think they're prepared for the truth, whatever it is. A lot of people don't believe anything about UFOs because of the absurd treatises that have come out on the subject. And a lot of people are afraid of the unknown. But the more we know, the greater the likelihood of treating UFOs in a friendly fashion.