On May 20, 2025, at the Sicheon factory in Gyeongsang South Province, South Korea, as the spotlight illuminates the metal skeleton number 001, the fifth-generation fighter independently developed by South Korea officially entered the mass production and assembly stage. This launch ceremony, led by the South Korean Defense Acquisition Program Administration (DAPA), not only brought together military and political leaders such as the Ministry of Defense and Air Force Command, but also attracted representatives from 37 military-industrial enterprises including the Hanwha system and LIG Nex1, marking the completion of a historic assembly of the South Korean military-industrial system.
This strategic leap began with a mass production contract of 1.96 trillion won (approximately US$1.4 billion) signed in June 2024. According to the agreement, South Korea Aerospace Industry Corporation (KAI) will deliver 20 Block 1 fighter jets within four years and simultaneously build a supporting logistics support system. At the subsequent production promotion meeting, the project team disassembled the entire machine into 138 key component modules, and achieved accurate docking of the front, middle and rear fuselage through a digital assembly system. It is worth noting that the mass-produced models introduced titanium alloy 3D printing technology for the first time, reducing the weight of the main beam structure of the wing was 23%. This breakthrough directly came from the data precipitation of more than 2,000 tests by 6 prototypes.
"Today is not only the start of the production line, but also the coming-of-age ceremony for the Korean aviation industry." Zheng Kyu-heon, director of the DAPA Future Forces Bureau, emphasized at the ceremony. The technocrat who led the localization of K2 tanks specifically pointed out that the KF-21 project has applied for 327 technical patents, of which 47% involve avionics system integration. The mass-produced AESA radar detection distance is 40% higher than that of the prototype. It can achieve multi-target tracking in complex electromagnetic environments with the new infrared search and tracking system (IRST). These technological breakthroughs directly led to procurement intention consultations in October 2024 in Poland, the UAE and other countries.
Behind this military-industry feast, the undercurrent international cooperation is more interesting. As the initial partner of the project, Indonesia's participation is continuing to shrink. The revised agreement in August 2024 limits Jakarta's technical participation to less than 15%, and the US$1.3 billion R&D funding it has still not yet been in place. This change prompted South Korea to adjust its mass production strategy, splitting the first batch of orders of 40 aircraft into two stages, and accelerating the integrated testing of Block 2 weapons. At present, KAI engineers are conducting supersonic bomb bay tests on the two-seater prototype to prepare for the equipping of European "Meteor" missiles.
Despite the constraints of the partners, the South Korean military-industrial complex has shown amazing integration capabilities. Among the more than 1,200 suppliers involved in the project, 87% achieved localized replacement, especially key components such as landing gear hydraulic systems broke the monopoly in Europe and the United States. This industrial resilience was fully revealed in flight tests at the end of 2024: 6 prototypes completed a total of 1,024 test flights, of which the two-seater type set a record of 4.2 hours of continuous flight, verifying the reliability of domestic engines. According to the roadmap disclosed by DAPA, the first mass-produced aircraft will be delivered to the Air Force in 2026 and will form initial combat power in 2028.
When the robotic arm of the Sicheon factory began to splice the first mass-produced aircraft body, South Korea was quietly rewriting the defense pattern in Northeast Asia. This stealth-shaped fighter will not only replace the old F-4 fleet, but its export prospects are more likely to leverage the global military trade market. As the US Defense News commented: "The mass production of KF-21 marks a qualitative change in South Korea from the equipment importing countries to the system exporting countries. The geopolitical shock caused by this transformation will far exceed the fighter itself."
