After 1948, the P-51 Mustang was renamed the F-51 Mustang (changing the P for pursuit for F for fighter).
History
Cold War
After the World War II and with the creation of the USAF in 1947, many piston engined fighter aircraft from World War 2 were replaced by jet aircraft. The F-51 was thus relegated to secondary duties.
F-51s were used by the ROCAF during the Chinese Civil War, with many of them falling into the hands of the PLAAF.
Korean War
F-51s based in Japan with the USAF's Far East Air Forces (FEAF) were among the first aircraft with the UN forces to see action against the KPAF and North Korea during Korean War in June 1950. Most of the F-51s were however waiting to be scrapped at Itazuke Air Base and Johnson Air Base in Japan.
On 26 June 1950, the FEAF had reassigned two F-51Ds from target towing to the ROKAF (which had earlier been decimated by the KPAF). Several US pilots were also reassigned to the same ROKAF squadron, the ROKAF 1st Fighter Squadron.
The RAAF also employed the F-51 (in this case, the Australian built CAC Mustang) in combat in Korea.