South Korea’s KF-21 Fighter Will Get A New Bunker-Busting Cruise Missile

South Korea is moving forward with plans to arm its homegrown KF-21 new-generation fighter jet with a locally produced air-launched cruise missile, or ALCM, the first of its kind to be produced by Seoul’s defense industry. Once fielded, that combination of fighter and long-range standoff missile will provide yet another means by which South Korea can attack targets deep within North Korea, including that country’s fast-developing nuclear weapons capabilities.

South Korea’s Defense Acquisition Program Administration, or DAPA, which is responsible for defense acquisition, including developing new weapons, confirmed yesterday that the new ALCM will be carried by the in-development KF-21, also known as the Boramae, meaning Hawk. DAPA says it will invest $145 million in the ALCM project, with the system development phase launched on the same day, December 12. The aim is to have the weapon in service by 2028.

A red-and-white-painted ALCM test round carried by an F-4E Phantom II fighter jet during trials. The new ALCM for the KF-21 is understood to be this same weapon or a development of it. YouTube Screencap

The Korea Times reports that the conventionally armed ALCM will have a range of at least 500 kilometers, or 310 miles, and will “become a core asset of the KF-21.” The same source notes that DAPA has so far not commented explicitly on the missile’s range but has confirmed that it will match that of the European-made Taurus KEPD 350K cruise missile, currently used by South Korea.

Getting an advanced new precision weapon on the KF-21 within six years sounds ambitious, but the ALCM has already undergone some testing in South Korea, between 2019 and 2021, including trial launches from F-4E Phantom II fighter jets. In this way, the basic feasibility of the project has been proven but it had not been confirmed until now that the missile, or a version of it, would arm the KF-21, which took to the air for the first time in July.

Aerial footage of the first prototype KF-21:

Reportedly named Cheonryong, or Sky Dragon, the new ALCM is being developed under the guidance of the Agency for Defense Development, or ADD, which will bring together different defense firms including Korea Aerospace Industries (KAI), LIG Nex1, and Hanwha Aerospace. KAI is also the prime contractor for the KF-21, and the other two companies also contribute to the fighter program. Seoul plans to field 120 Block 1 KF-21s by 2032, before further developing the aircraft in the more advanced Block 2 configuration.

During its first flight, the KF-21 prototype was fitted with four mock-ups of the long-range Meteor air-to-air missile (AAM), carried in their semi-conformal location under the fuselage. However, the jet is designed to be fully multirole, with offensive weapons options also including the GBU-12 Paveway IIGBU-31/38 Joint Direct Attack Munition (JDAM), GBU-54/56 Laser JDAMGBU-39/B Small Diameter Bomb I, and the CBU‐105 Wind Corrected Munitions Dispenser (WCMD). Like the KEPD 350K, these offensive stores are currently all already used by the Republic of Korea Air Force, or ROKAF.

The new ALCM, therefore, appears to be the first locally developed weapon to be confirmed for the KF-21.

KF-21 takes to the air. ROK Air Force

The new missile will be something of a follow-on from the KEPD 350K, which is the product of a joint venture between MBDA Deutschland of Germany and Saab Dynamics of Sweden. According to open-source information, South Korea bought its first batch of 170 KEPD 350Ks in 2016 and then ordered another 90 examples in late 2016, in the wake of a North Korean nuclear test.

The Korean-specific KEPD 350K is an improved version of the basic KEPD 350 that was ordered by Germany and Spain. Measuring 16 feet 5 inches in length, the KEPD 350K weighs 3,100 pounds. Its guidance system combines GPS and inertial navigation systems. An imaging infrared sensor in the nose is used for image-based terrain-reference navigation.

A German Eurofighter EF2000 jet carrying a pair of Taurus KEPD 350 cruise missiles. Philipp Hayer/Wikimedia Commons

Critically, for its role with the ROKAF, the KEPD 350K uses a dual-stage warhead that is able to penetrate around 20 feet of concrete, meaning it can destroy heavily fortified bunkers, including North Korean command and control and leadership infrastructure.

In ROKAF service, the KEPD 350K is carried exclusively by the F-15K Slam Eagle, an advanced derivative of the F-15E Strike Eagle.

An F-15K Slam Eagle armed with a pair of KEPD 350K cruise missiles. MBDA

Exactly what relationship the homegrown ALCM will have to the KEPD 350K is unclear, although it’s likely no coincidence that it’s being reported as having a range in the region of 310 miles, putting almost every target in North Korea within reach of the missiles, without their launch aircraft having to leave South Korean airspace. At the same time, the KEPD 350K deal included some technology transfers — including transfers relating to the penetrator warhead — that will undoubtedly have helped develop a homegrown cruise missile.

At one stage, it was reported that South Korea was looking to acquire a smaller and lighter version of the KEPD 350K that would be able to arm jets like the FA-50 Fighting Eagle light combat aircraft, as well as the KF-21. This weapon was said to have a range in the region of 400 kilometers or around 250 miles. However, it seems that the work on this project was abandoned and that the new ALCM is a different design.

According to the International Institute for Strategic Studies (IISS), research and development of the new ALCM began in December 2016. Then, starting in 2018, ADD cooperated with LIG Nex1, on initial development work. A mock-up that likely represented the ALCM was shown at the Aerospace & Defense Exhibition (ADEX) in Seoul in 2019, as seen in the video below. This is broadly similar to the configuration of the KEPD 350, with folding wings that pop out from in top of the missile body and cruciform tail fins, although with characteristic chines along the sides of the body and a faceted nose section, that appear to be intended to reduce its radar cross-section.

Early reports described a 3,000-pound weapon, making it roughly the same weight as the KEPD 350K, and, as already noted, also offering a similar range, in the region of 310 miles.

In September last year, meanwhile, Seoul unveiled a new ALCM, one of four new missiles, just two days after North Korea revealed a land-attack cruise missile of its own. As expected, the South Korean ALCM has a superficial resemblance to the KEPD 350K, but it’s unclear if or how it may change as part of its optimization for the KF-21. The disclosure in September 2021 also included a video, showing a live-fire launch of the ALCM from an F-4E, as well as the apparent impact on a target range.

Imagery from the test launch of the new South Korean ALCM that was announced in September 2021. YouTube Screencap
The Taurus KEPD 350, showing the folding wings on top of the missile body. Alf van Beem/Wikimedia Commons

In its initial form, the KF-21 carries its weapons externally, or semi-conformally, although the future Block 2 version of the jet is planned to feature internal weapons bays. It’s possible that the ALCM might be tailored for internal carriage or be modified as such in the future. However, its long standoff range means the launch aircraft does not necessarily even need to penetrate North Korean airspace, so external carriage may be considered suitable, even for the stealthier Block 2 KF-21.

A map showing the approximate range of a 300-mile-capable ALCM were it to be launched in South Korean airspace close to the border with North Korea. Google Earth

Whatever its ultimate appearance, having access to a domestically produced ALCM is a big deal for South Korea.

The KEPD 350K was originally procured primarily due to U.S. reluctance to supply long-range ‘bunker-busting’ weapons of the kind that South Korea needs. At the same time, both Germany and Sweden have notably tight arms export regulations. While the ROKAF seems happy with its KEPD 350Ks, the continued supply of these weapons, as well as support and spares, cannot be guaranteed, especially in wartime or periods of considerably increased tensions on the peninsula.

Having access to locally made weapons in this class avoids reliance on arms imports and, at the same time, allows Seoul to offer the ALCM for export itself and to continue building up its impressive defense industry. We have already examined how the KF-21 could be a very attractive export prospect, with claims of better kinematic performance than an F-16C and an active electronically scanned array (AESA) radar, produced locally by Hanwha Systems. The option of an ALCM makes the overall KF-21 offer more compelling, especially to customers that might not be able to access U.S.-made standoff weapons.

Concept artwork of a KF-21 armed with four semi-recessed Meteors, IRIS-T self-defense missiles, and a pair of JDAMs. MBDA

More important than all this, of course, is what the new ALCM promises to bring to Seoul’s military posture.

The ALCM fits squarely into Seoul’s so-called three-axis operational plan, designed to dissuade or respond to a possible nuclear attack from North Korea.

A Republic of Korea Air Force F-35A stealth fighter drops a laser-guided bomb during joint air drills in response to the North Korean intercontinental ballistic missile (ICBM) test launch on November 18, 2022. Photo by South Korean Defense Ministry via Getty Images

The first tenet of the plan is the kill chain element that’s intended to carry out a preemptive strike against Pyongyang’s nuclear and missile facilities to defend Seoul if necessary.

Secondly, the Korea Air and Missile Defense network is intended to destroy North Korean ballistic missiles targeting the South once they have been launched.

Thirdly, there’s the Korea Massive Punishment and Retaliation program, or KMPR, also known as Overwhelming Response, an effort to develop ways to retaliate against North Korea, using conventional weapons, should Pyongyang launch a first strike. Clearly, a precise cruise missile with bunker-busting capability would contribute greatly to KMPR, including the ability to strike key leadership facilities and command and control nodes. There may also be an option of adapting the ALCM design for different ground-launched or surface-launched applications, too.

The KMPR concept will also rely on other new-generation long-range weapons, including Seoul’s latest Dosan Ahn Changho class diesel-electric attack submarines, also known as the KSS-III, which are designed to provide a highly survivable strike capability using their conventionally armed submarine-launched ballistic missiles (SLBMs).

Although the KMPR initiative is currently based around conventional weapons, there has long been speculation that Seoul might one day commit to developing nuclear warheads, too. While SLBMs would be the obvious choice for these, adaptation of the ALCM for a nuclear payload could also be a possibility. Just having the option to adapt the missile to a nuclear role is a key factor in itself.

It’s unclear what, if any reaction, Seoul’s ALCM program will have on North Korea, although the latest development comes in the wake of heightened tensions on the peninsula, including a tit-for-tat campaign of weapons launching displays in recent months. This included North Korea firing a ballistic missile across the de-facto maritime border with South Korea, for the first time, last month.

Seoul’s plans to field a new ALCM on its advanced KF-21 fighter jet once again highlight the considerable investments the South is making in its precision-strike capabilities, something that’s only likely to continue as long as Pyongyang continues to expand its nuclear attack options.

Contact the author:

Thomas Newdick Avatar

Thomas Newdick

Staff Writer

Thomas is a defense writer and editor with over 20 years of experience covering military aerospace topics and conflicts. He’s written a number of books, edited many more, and has contributed to many of the world’s leading aviation publications. Before joining The War Zone in 2020, he was the editor of AirForces Monthly.