February 1, 2026: The South Korean KF-21 jet fighter will enter service next month, and delivery of the first 40 Block 1 air superiority aircraft will be completed in 2028. After that, 80 Block 2 fighter-bombers are to be ordered and delivered by 2032. The Block 3 stealth version will show up sometime in the 2030s. This year South Korea began development of a South Korean engine for the KF-21. The new engine will be available when the Block 3 aircraft arrives in the 2030s. Block 1 and 2 aircraft will also be able to use the South Korean engines. Jet fighters wear out several engines during their usual 30-40 years of service. The current engine for the KF-21 is the American GE F414, which is built under license in South Korea. The South Korean engine will be built by Hanwha.

The KF-21 project began in 2010. South Korea sought nations willing to cooperate in developing the new fighter by providing some of the money needed to complete the program and then purchase some of the fighters. Indonesia agreed to such a deal but proved to be an unreliable partner. Indonesia did not provide the promised funding and then Indonesian engineers involved with the project were caught trying to steal the jet fighter technology South Korea had already developed. The Indonesian government insists it knew nothing about the attempted technology theft and that it would catch up on missed payments it promised in order to become a 20 percent partner in KF-21 development. Indonesia was unable to provide the money, more than a billion dollars, to retain a 20 percent stake in the project. Instead, Indonesia paid $439 million for a 7.5 percent stake in the project and lower priority in receiving KF-21s.

Poland offered to be a development and production partner. Poland can afford this and has its own industrial base that is capable of co-producing KF-21s. Poland plans to join the program this year, after development of the Block 1 model of the KF-21 is complete and work begins on the Block 2 model. The United Arab Emirates and Saudi Arabia are interested in acquiring KF-21s.

KF-21 development began in 2011 and the first KF-21 test flight was in 2022. Development costs of the KF-21 were over $8 billion and each aircraft costs $65 million to build. That is a competitive price for a modern jet fighter.

This all began in 2001 when South Korea announced the KF-X advanced multirole jet fighter project. South Korea wanted to develop and manufacture a modern jet fighter to replace its 167 F-16s, 19 F-4s that were retired in 2024, and 80 F-5s. The 59 F-15K fighter-bombers will remain in service until about 2030. In addition to KF-21s, South Korea already has 39 F-35s, with 20 more on order. The F-16s will be gradually replaced by F-35s and KF-21s.

The preliminary KF-21 design was completed in 2018 and approved in 2019. In 2022 six KF-21 prototypes made their first flights in 2023. These six prototypes continue to be used for flight tests and performance verification. The prototypes are not identical and are modified to keep up with what the final KF-21 aircraft will be. South Korea spent about $50 million to develop the KF-21, which is a 25 ton, twin-engine, single seat fighter bomber. The engines are American F414 models built in South Korea under license. Up to 7.7 tons of weapons can be carried for surface attack missions. There is an internal 20mm autocannon with 480 rounds of ammunition. Max combat range is 1,000 kilometers while ferry range, carrying only additional fuel pods, is 2,900 kilometers.