Answer these questions first. How large were they, how high up were they and how far out. What was their estimated speed. What known crafts on earth (russian or american, british or any other developed nation) had the ability to travel at these speeds and altitude. Then, assuming there were some crafts capable, ask how many were known to exist at that period. If you can show me that we had that many crafts that could travel at those speeds and that were that size and that high up, then there is most likely your answer. Otherwise, Its not of this earth. Was it pieces of space rocks bouncing off of our atmosphere? or was it intelligently controlled?