While viewing the Perseid meteor shower in the high desert near Mono Lake and the California-Nevada border two separate incidents occurred of the same object within a 20 minute period. This was witnessed by multiple observers.

1)  A very bright white light flashed on the south horizon and proceeded to the north horizon, flashing irregularly, but frequent enough to track its trajectory easily.  It traveled faster than anyone present had ever previously observed.  The flashes were one to two seconds in duration.  It appeared to be in the upper atmosphere, substantially higher than the many aircraft nearly constantly present.  We also saw plenty of satellites, which moved at a fraction of the object.  I estimate it traveled from horizon to horizon in less than 15 seconds.
2)  Approximately 20 minutes later the light reappeared, but this time it was directly in the center of our field of view, around 35-40 degrees above the horizon.  It flashed with the same frequency, but remained near motionless in the sky.  I believe it did move, but so little some of us felt it was completely motionless.  It remained in position for approximately 5 minutes, and then stopped flashing. When it was not lit, the sky appeared empty at its location.
I am an Air Force vet, trained weather observer, and this event was unique in my experience.  This was no meteor, of which we saw many.
None of us had an explanation for what we saw beyond the possibility that we witnessed secret technologies of our military (our location was approximately 120 miles from the Groom Lake, NV area), or a UFO of extraterrestrial origin.  This was pure speculation, and the entire incident remains a puzzling mystery.
I do note that this sounds very similar to the descriptions of others on this site.