South Korea's homegrown KF-21 fighter jet passed a provisional combat suitability evaluation earlier this week, the state arms procurement agency said Tuesday, in a key milestone ahead of its initial production phase set to begin next year.

The Defense Acquisition Program Administration said the evaluation by the Joint Chiefs of Staff came Monday, based on the outcome of hundreds of flight and ground tests on the jet that have proceeded for some two years.

The "provisional" evaluation scheme has been introduced to allow weapons developers to secure mass-production budgets even before prototypes meet all combat requirements in an effort to accelerate the overall production process.

"This evaluation has laid the foundation, upon which we can proceed with the initial mass-production plan next year," DAPA said in a press release.

Since the rollout of the first KF-21 prototype in April 2021, the authorities have conducted various tests, including around 200 flight tests, to check some 260 testing items, including the flight speed, combat operational range, and takeoff and landing distances.

A total of six KF-21 prototypes, manufactured by Korea Aerospace Industries Ltd., are set to undergo a combined 2,200 flight tests through 2026 to confirm the jet's overall capabilities.

Launched in 2015, the 8.8 trillion-won ($6.59 billion) KF-21 project is aimed at developing a supersonic fighter to replace South Korea's aging fleet of F-4 and F-5 jets. (Yonhap)