Air Force Chief of Staff Gen. Lee Seong-yong was to visit Korea Aerospace Industries (KAI) on Tuesday to check the development of the country's first indigenous fighter jet, the military said.

The visit to KAI, the country's sole aircraft manufacturer, in the southern city of Sacheon comes as the final assembly of a prototype of the KF-X warplane is under way ahead of its planned rollout event in April.

South Korea has been working on the 8.8 trillion-won ($7.9 billion) fighter project since late 2015 to replace the Air Force's aging fleet of F-4 and F-5 jets.

"The Air Force will use all available resources to support the successful development of the KF-X program," he said, calling on the company to work on the project with a sense of duty.

The combat plane's first flight test is scheduled for 2022, with the entire development set to be completed by 2026.
When the development is complete, 40 units will be delivered to the Air Force by 2028 and another 80 units by 2032, according to officials.