South Korea Officially Enters Elite Club With Home-Grown KF-21 Fighter Jet, Here’s How It Stacks Up Against Tejas And F-35

South Korea just hit a major milestone: its first homegrown fighter jet, the KF-21 Boramae, is about to join the air force. This isn’t just a new plane; it’s a sign that Seoul is serious about building its own advanced military tech, especially with all the tension in the region lately.

All about South Korea’s KF-21 Fighter Jet

The KF-21 is a twin-engine multirole jet, and people usually call it a “4.5-generation” fighter. Basically, it’s set to take over for the old F-4s and F-5s that the Republic of Korea Air Force has been flying for decades.

Korea Aerospace Industries (KAI) kicked off the project back in 2010. Fast forward to now, and the KF-21 has logged more than 2,000 hours of test flights. The air force will start getting the new jets this year, and KAI already has upgrades in the works for later versions.

Tech-wise, the KF-21 packs some serious gear. There’s an AESA radar, fly-by-wire controls, and some stealth features to help it avoid enemy radar.

Right now, the jet carries its weapons outside on hardpoints, but South Korea plans to build future models with internal bays for better stealth.

South Korea’s KF-21 goes 2,300 kilometres per hour

It’s fast, too, about 2,300 kilometres per hour, so it’s a nimble, affordable rival to expensive fifth-gen jets like the American F-35.

The project isn’t just a solo effort, either. Indonesia helped fund it, and other countries, think the Philippines and Malaysia, are showing interest.

This all comes as South Korea’s defence industry is making a name for itself globally. Just look at how well the K2 main battle tank and K9 self-propelled howitzer have sold overseas. 

How KF-21 Compares to Tejas and F-35

The KF-21 gives South Korea a real edge in the regional aerospace race. Other countries, like India with its Tejas and Turkey with the KAAN, are also working on their own fighters. Still, China’s J-20 stealth fighter is the heavyweight here, even if details about its tech are mostly under wraps.

For South Korea, the KF-21 is more than just a new jet. It’s a symbol—a sign that the country has the know-how and independence to build what it needs, on its own terms, as it faces whatever comes next in East Asia.

Local news says they’ll deliver the first mass-produced jets in 2026, once they wrap up acceptance tests. This isn’t just any delivery, either. It’s the first time South Korea’s rolling out a homegrown fighter jet, with Korea Aerospace Industries leading the charge.

Will KF-21 replace F-4 Phantom II? 

The KF-21, or KF-X, stands out as one of South Korea’s boldest defence projects. The goal? Replace those old F-4 Phantom IIs and F-5 Tiger IIs and cut down on depending on foreign jets.

Since the prototype took off in 2022, they’ve put several test jets through their paces, checking flight performance, avionics, and mission systems. Full-scale production kicked off in 2024, and assembly of the first operational jet wraps up in 2025.

The first jets off the line are Block I models, set up mainly for air-to-air combat. These planes will reach initial operational status first, with even more advanced Block II versions coming later this decade. 

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