KF-21: Meet South Korea's Powerful 'Stealthy' Fighter (Mini F-35?)

May 11, 2024 Topic: Security Region: Asia Blog Brand: The Buzz Tags: KF-21South KoreaKF-21 BoramaeF-35MilitaryDefenseChina

KF-21: Meet South Korea's Powerful 'Stealthy' Fighter (Mini F-35?)

It will not be a true fifth-generation fighter, but the KF-21 is expected to have a lower radar cross-section than existing fourth-generation fighters.


Summary: Negotiations between Indonesia and South Korea continue over the KF-21 fighter jet development. Indonesia seeks to reduce its contribution from 1.6 trillion won to 600 billion won, which South Korea is considering.



-The KF-21, not a full fifth-generation fighter but with stealth-like features, is expected to debut in 2026.

-It aims to replace South Korea's older F-4 Phantoms and F-5 Tigers, amidst regional advancements like China's J-20 fighter. South Korea's Defense Acquisition Program Administration (DAPA) reassures that financial adjustments will not delay the project.

The Future of Air Combat: Inside the KF-21 Development Amidst Indonesia-South Korea Negotiations

Negotiations drag on between Indonesia and South Korea over the development of the Korea Aerospace Industries KF-21 fighter. 

Indonesia demands that their payment for the new fighter be reduced by 63%, and Seoul is reportedly open to accepting Jakarta’s proposed cuts. According to the Korea Herald, South Korea’s Defense Acquisition Program Administration, or DAPA, said “the reduction in the Indonesian contribution to the joint project was expected to translate into less of a financial burden than speculated…expenses could be cut down considerably over the process.” 


The KF-21 program was expected to cost about 8.1 trillion won (nearly $6 billion). But DAPA now believes the program will cost 7.6 trillion won, and if that is the case, the Koreans would discount the difference.

“We will be doing our best to make up for the possible shortages in funds that can arise from the adjustments in Indonesian input,” a DAPA official said. “Once again, our top priority is not to let the project timeline be stymied by delays on Indonesia’s part.”

Indonesia was expected to contribute 1.6 trillion won. Jakarta wants to reduce its contribution to just 600 billion won.

“We are open to accommodating Indonesia’s suggestion and adjusting its share to an amount it is able to pay,” the DAPA official said.

What Is the KF-21?

If projections hold, the KF-21 will be introduced in 2026 regardless of Indonesia’s contribution. The aircraft is billed as a modern fighter jet with stealth capabilities. It will not be a true fifth-generation fighter, but the KF-21 is expected to have a lower radar cross-section than existing fourth-generation fighters.

The KF-21 surely looks like a fifth-generation fighter. It very specifically resembles the Lockheed Martin F-35 Lightning II.

Of course, what makes the F-35 so capable is the fighter’s avionics, which allow for best-in-class sensor fusion and situational awareness. The South Koreans might emulate the flight surfaces and outward appearance of the F-35, but they will not be able to reproduce the electronic heart that makes the fighter so capable.


The KF-21 is slated to be a multirole fighter that can replace South Korea’s aging fleet of F-4 Phantoms and F-5 Tigers. These were capable fighters when they debuted, in 1958 and 1963 respectively. The U.S. developed both aircraft and phased them out so long ago that their replacements – the F-14, F-15, F-16, and F/A-18 – are themselves now quite aged.

The South Koreans are due for an update, especially as China works to refresh its air force. Beijing has unveiled its own F-35 rip-off, the Chengdu J-20 fighter, and is working to build a stealth bomber, the Xi’an H-20. If South Korea wants to keep pace in the Indo-Pacific, they will need fresher, stealthier fighters.   

About the Author: Harrison Kass 

Harrison Kass is a defense and national security writer with over 1,300 total pieces on issues involving global affairs. An attorney, pilot, guitarist, and minor pro hockey player, Harrison joined the US Air Force as a Pilot Trainee but was medically discharged. Harrison holds a BA from Lake Forest College, a JD from the University of Oregon, and an MA from New York University. Harrison listens to Dokken.