Group of USAF cadets and an officer saw a saucer at an air force base.

This is not an air sighting. I was a member of a group of AFROTC visiting group to Eglin AFB in 1978.  This group consisted of ten cadets (six under contract to the USAF including myself) and a Lt. Col., our advisor.  During our visit we were touring the base in a USAF bus, much like an old school bus painted a blue/gray.
We were trans-versing the flightline between many large hangers, mostly closed.  We came to a stop at a crossroads stop sign.  I happened to look to our left into an open hanger and saw a saucer-shaped craft approx. 30 feet across with a central dome.  The craft stood on three spindly legs that did not look capable of holding up such a large craft.  There were USAF markings on the upper portion, much like fixed-winged aircraft.
I called it to the attention of others, five were pretty close friends.  Several took snapshot pictures of the craft.  The officer with us definitely saw the craft as well.  We observed the craft for at least four minutes, till the bus moved past the stop sign.
Within 50 feet, our bus was surrounded by AF Security Police, in full combat gear, in jeeps and trucks.  The officers entered our bus and took everyone's cameras and removed the film on the spot!  We were hustled the bus into a nearby hanger serving as offices.  We were officially debriefed and sworn to secrecy under threats of prison for revealing anything about what we had observed in the hanger, then released.  These people were dead serious.
Most of us continued our careers into the Air Force, myself into the Security Police, and others became pilots and missile men.  The officer with us became a Congressman after retiring from the military.
I have not revealed this information ever, until now.  What the hell, I'm 60 and dying of ((type of malady deleted)), what can they do to me?