The Korean War has been called “the forgotten war,” and “Missing in MIG Alley,” on PBS on Tuesday night, illustrates a little-known chapter. It describes the rivalry in the sky between two types of fighter jets then on the cutting edge of military aviation: the Soviet MIG-15, used by the North Koreans, and the F-86 Sabre, flown by the Americans and the British.

The bulk of the dogfights took place south of the Yalu River on the border between North Korea and China, in a track of space known to pilots as MIG Alley.

The program, an installment of the “Nova” series, reveals that Soviet airmen were actually fighting on behalf of the North Koreans, a fact concealed by the Soviet and American governments at the time for fear of inciting World War III. (This secret may prompt viewer speculation about possible clandestine maneuvers today.)