Objects were tracked by radar and sighted visually. Multiple independent witnesses.

Two lights, the size of a star, were observed by six male witnesses two of them independent, four of them an experienced observors, at an airfield for five to seven minutes.

Hynek: Observations made by four expert air traffic control observers in a deep blue twilight sky, moon present but stars not yet visible. They contacted Great Falls radar by telephone and the presence of an erratic was confirmed to them (but then denied the next day by the Air Force and FAA). One ATC reported:

I've been working in this tower for 27 years, and I've never seen anything like this before. ... It was the violent maneuver . . . and the apparent cooperation between the two bright objects that made the sighting significant….The two objects were just bright points of white light and could have been taken for satellites except for the sudden maneuvers, change of direction, and speed of disappearance .... One was headed north at 45 degrees above the horizon, the other south at about 30 degrees. The southbound light executed a sudden 180-degree turn, rose, joined the other object, hovered in what appeared to be a formation, and then flew off to the northeast.

Google map of this location.