On December 17, 1950, the first known aerial combat between swept-wing jet fighters took place in the skies over Korea. The Russian-built Mikoyan-Gurevich MiG-15 had been recently introduced and its speed and maneuverability caused trouble for the United States and in response, the North American F-86 Sabre was rushed to Korea. Ward Hitt, Jr., a member of the 4th Fighter Interceptor Group, chronicled the early days of the F-86 in combat in a detailed scrapbook.