Korean reunification selected the 38th parallel as a dividing line. Japanese troops to the North of this line were to surrender to the Soviet Union and troops to the South of this line would surrender to the United States. This was not originally intended to result in a long-lasting partition, but Cold War politics resulted in the establishment of two separate governments in the two zones in 1948 and rising tensions prevented cooperation. The desire of many Koreans for a peaceful unification was dashed when the Korean War broke out in 1950. In June 1950, troops from North Korea invaded South Korea.
Soviet Union in the Korean War pilots flying MiG-15 jets participated in battles around the Yalu River Valley on the Chinese-Korean border in the area known as "Mig Alley" and in operations against UN "trainbusting" attacks in Northern Korea, with considerable success. The lack of a shared language between Soviet, Chinese and North Korean pilots frequently led to incidences of friendly fire as other MiG fighters were mistaken for American F-86 Sabre jets and shot down. The MiG-15 was a jet aircraft, supplied in large numbers to Chinese and North Korean forces during the war by the Soviet Union. Owing to their modern design (they were