While the MiG-15bis introduced swept wings to air combat over Korea, the Mikoyan-Gurevich design bureau had already begun work on its replacement in 1949 (originally the MiG-15bis45) in order to fix any problems found with the MiG-15 in combat. The result was one of the most successful transonic fighters introduced before the advent of true supersonic types such as the Mikoyan-Gurevich MiG-19 and North American F-100 Super Sabre. The design would ultimately still prove effective into the 1960s when pressed into subsonic dogfights over Vietnam against much faster planes which were not optimized for maneuvering in such slower speed, short-range engagements.