During the late 1960s, 92 F-5A and 23 F-5B Freedom Fighters were acquired by the government of Taiwan through the MAP and FMS programs. However, about half of these aircraft were sent to Vietnam, and the remainder were transferred to two reserve units.
In the early 1970s, Taiwan initiated a modernization program for the Republic of China Air Force (Ching-Kuo Kung Chuan). In 1973, an agreement was reached for the local assembly of 100 F-5Es. Production was to be undertaken by the Aero Industry Development Center (AIDC) at Shuinan. The aircraft was to be known locally as the Chung Cheng.
In 1979, the United States withdrew all of its troops and cancelled the 1954 mutual defense treaty with Taiwan in an attempt to improve relations with the People's Republic of China on the mainland. This lessened the amount of support available from Northrop, forcing Taiwan to increase the amount of locally-produced components for the Chung Cheng program. The last AIDC-built Chung Cheng was delivered in 1986, resulting in the delivery of 242 F-5Es and 66 F-5Fs to the RoCAF. Many Taiwanese-built F-5Es have an F-20-style flattened nose, enlarged LERXes, and some from the last two batches are compatible with the AGM-65 Maverick.
The F-5Es replaced both the F-100 Super Sabre and the earlier F-5A/B in ROC AF service. The Tiger IIs are used in both the air-to-air and air-to-ground roles. F-5Es serve with the 1st, 4th, 5th, 7th, and 8th Wings, which are based at Tainan, Chiayi, Tao Yuan, Taitung-Chih Hang, and Hualian (Hsinchua?) respectively. These five wings fall under the control of Combat Air Command, and each wing typically has 3 squadrons of 18 aircraft each. The 5th Tactical Combined Wing is a fighter reconnaissance wing which operates RF-104s along with its F-5s. The 7th TFW is the training unit, which also operates the aggressor unit, the 46th TFS. The inclusion of large numbers of defectors from the mainland in the Taiwanese armed forces enables the aggressor training program to be especially accurate in simulating the tactics of their most likely opponent.
Substantial numbers of F-5As are still in service, although many of the survivors were converted into drones during the 1980s.
During the 1980s, Taiwanese F-5s have been upgraded with the addition of Litton ALR-46(V) 3 RWRs, Northrop AVQ-27 laser designators and Tracor ALE-40(V)7 chaff/flare dispensers. In addition AGM-65 Maverick air-to-surface missiles and Paveway II laser-guided bombs have been acquired.
Taiwan also tried to upgrade theIR-5E/F fleet with AIDC's Tiger 2000/2001 program. The first flight took place on 24 July 2002. The program would replace the F-5E/F's radar with F-CK-1's GD-53 radar and allow the fighter to carry a single TC-2 BVRAAM on the centerline. But lack of interest from the Taiwan/ROC Air Force eventually killed the program. The only prototype is on display in AIDC in Central Taiwan
Today, the F-5 is still the most numerous fighter aircraft in service with the RoCAF. However, Taiwan has made repeated requests to the USA for more advanced combat aircraft, but these have all been politely rebuffed. In 1985, AIDC launched an indigenous fighter project known as the Ching-Kuo to replace the remaining F-104s and the F-5s. It has entered squadron service, but further production of the Ching-Kuo was suspended in late 1995 when flaws were found in the fuel system. In that year, the USA finally relented and agreed to release the export of 150 F-16A/B Block 20 aircraft to Taiwan.
Perhaps the most ambitious F-5 upgrade program of them all is the proposed F-5E-SX. This will replace the twin J85s with a single F-125X turbofan and add a new multimode radar, perhaps the indigenous Sky Dragon derivative of the AN/APG-67. However, it appears likely that any future upgrades to Taiwan's F-5 fleet will be far more modest in scope.
With the introduction of 150 F-16s, 60 Mirage 2000-5s and 130 F-CK-1s in mid-to-late-1990s, the F-5E/F series became second line fighters in ROCAF service and mostly are now withdrawn from service as squadrons converted to new fighters entering ROCAF service. Seven low airframe hours F-5Es were sent to ST Aerospace to convert them to RF-5E standard to fulfill a reconnaissance role previously undertaken by the retiring Lockheed RF-104G In ROCAF service. As of 2009, only about 40 ROCAF F-5E/Fs still remain in service in training roles with about 90–100 F-5E/Fs held in reserve. The other retired F-5E/F are either scrapped, or used as decoys painted in colors representing the main front line F-16, Mirage 2000-5 or F-CK-1 fighters, and deployed around major air bases
The only air combat actions ROCAF F-5E/F pilots saw, were not over Taiwan, but in North Yemen. In 1979, a flareup between North Yemen and South Yemen prompted the U.S. to sell 14 F-5E/Fs to North Yemen to boost its air defense. Since no one in North Yemen knew how to fly the F-5E/F (only MiG-15s were operational at the time), U.S. and Saudi Arabia arranged to have 80+ ROCAF F-5E pilots plus ground crew and anti-air defense units sent to North Yemen as part of North Yemen Air Force's 115th Squadron at Sana‘a operating initially just six F-5E/Fs and then from April 1979 to May 1990, added eight more. The ROCAF piloted F-5E/F scored a few kills in a few air battles, but the ground early warning radar crews and anti-air units also suffered from air attacks from South Yemen, whose aircraft were piloted by Soviet crews
The following units have used the F-5: