The Republic of Korea Air Force (Hankook Kong Goon) is a major operator of the F-5, and flies all versions of the F-5 with the exception of the RF-5E.
The ROKAF received its first early-model F-5 Freedom Fighters in 1965, and operated a large number of F-5Aa, F-5Bs, and RF-5As. As a favor to the United States, in 1972, Korea transferred 36 F-5As and all its RF-5As to the Republic of Vietnam Air Force. To make up the difference, the US government agreed to supply Korea with F-4 Phantoms and later-model F-5Es. The first F-5Es entered Korean service in 1974, when 19 ex-Vietnamese Air Force aircraft were delivered. This laid the foundation for the acquisition of 126 new-build F-5Es and 20 F-5Fs. The first F-5Es were allocated to the 1st Fighter Wing (115th, 122nd, and 123rd Tactical Fighter Squadrons) based at Kwang Ju air base.
In 1980, South Korea signed an initial license production agreement for the manufacture of 48 F-5Es and 20 F-5Fs plus their engines. The Hanjin Corporation, utilizing some facilities owned by Korean Air Lines, assembled the last 68 of the 233 F-5E/Fs delivered to the ROKAF between 1974 and 1986. The General Electric J85 engines were assembled by Samsung (today known as Samsung Aerospace Industries). Work on the project began in 1981, and the first Korean built F-5 (an F-5F) flew for the first time on September 9, 1982. The Korean-built aircraft had all been delivered by 1986.
These F-5E/Fs replaced the previous force of F-5A/Bs, although some of these are retained for training. In ROKAF service, the F-5 is known as the Chegoong-ho (Skymaster). The South Korean government is very tight about security, and very little reliable information is available about serial numbers and unit allocations. However, it is believed that the F-5E equips the 115th, 122nd, and 123rd TFS of the 1st Fighter Wing based at Kwangju, the 102nd, 103rd, and 111th TFS of the 10th Fighter Wing (the 102nd and 103rd are based at Suwon, but the 111th is a geographically separated unit stationed at Kunsan), and the 201st and 203rd TFS of the 5th Fighter Wing (base unspecified). The Operational Conversion Unit for the 1st Fighter Wing retains some F-5A/Bs for training.
The last of the F-5A/Bs were retired by August of 2007, and they were replaced by the F-15K and by the indigenous
KAI F/A-50. The RoKAF currently operates 170 F-5E/Fs and KF-5E/Fs. Current plans are for
these aircraft to be replaced by the indigenous KAI F/A-50 Fighting Eagle and by the Lockheed Martin F-35A Lightning II.