U.S. Approves SM-6 Missile Sale to South Korea: Game-Changer in Regional Defense

Enemy missiles intercepted at altitudes up to 35 km
Capable of intercepting even hypersonic missiles with upgraded versions
Backbone of the U.S. Navy’s next-generation missile defense system
SM-3 was unable to intercept North Korean large-caliber artillery

The USS John Paul Jones (DDG-53) is pictured launching a new SM-6 interceptor missile. The missile successfully intercepted a medium-range ballistic missile that was test-launched from a base in Kauai, Hawaii. Photo credit: U.S. Navy

The U.S. government has provisionally approved the sale of the SM-6 interceptor missile, with a maximum range exceeding 400km (248.5 miles), to South Korea, sparking interest in this weapon system. This acquisition’s ultimate objective is to enhance further South Korea’s ability to intercept North Korean missiles.

The Defense Security Cooperation Agency (DSCA) under the U.S. Department of Defense announced on the 14th (local time) that the U.S. government has provisionally approved the sale of SM-6 fleet air defense missiles to South Korea through the Foreign Military Sales (FMS) method. The State Department has approved the purchase of SM-6 missiles and related equipment worth $650 million, as the South Korean government requested. The final sale will be executed after approval from Congress, which is expected to approve without raising any significant issues. The South Korean government is known to have requested the purchase of up to 38 SM-6 missiles.

In March, the Korean Defense Acquisition Program Administration held the 150th Defense Acquisition Program Promotion Committee and decided to secure U.S.-made SM-6 missiles through the FMS method to be mounted on the KDX-Ⅲ Aegis destroyer. The SM-6, with a maximum range exceeding 400km (248.5 miles), employs an active guidance system that allows the missile to track targets directly with its own radar, greatly enhancing the simultaneous engagement capability of the ship. It can intercept ballistic missiles and aircraft, ships, and cruise missiles. The U.S. decided to sell it to Japan last year.

The day after the news of the SM-6 introduction, North Korea revealed that it had successfully tested a solid fuel engine for its new medium-range ballistic missile (IRBM). North Korea has previously showcased its capability to strike the U.S. mainland by test-firing the Hwasong-18, a solid-fuel intercontinental ballistic missile (ICBM). Now, it is on the verge of completing a new IRBM. The new IRBM can hit targets as far as Guam, the base of U.S. strategic assets, in addition to the Korean Peninsula. Notably, the solid fuel missile, which can be launched by surprise and is difficult to detect before launch, is a weapon system that keeps the U.S. and South Korean military authorities on edge.

The DAPA emphasizes that the SM-6 is an asset of the Korean missile defense system (KAMD), a system to defend against North Korean missiles in an emergency.

The introduction of the SM-6 draws attention as it is one of the three axes of the Korean system, along with the kill chain that strikes preemptively when North Korea tries to launch nuclear missiles and the Korea Massive Punishment and Retaliation (KMPR) that retaliates when North Korea attacks with atomic missiles. With the introduction of the SM-6, a more dense maritime air defense network can be formed, which will enhance the ability to respond to North Korean ballistic and cruise missiles, according to the judgment of our military authorities.

The SM-6 interceptor missile, which will be first mounted on the latest Aegis ship, the King Sejong the Great, is known to be able to intercept (improved) not only aircraft, ships, and ballistic missiles but also hypersonic missiles that are emerging as game changers.

A military source said, “We will first introduce it as an interceptor missile to protect our naval ships,” and “We should focus on the necessity of introduction, considering that the improved SM-6 will also have the ability to intercept hypersonic missiles in the future.” In other words, the most significant advantage of the SM-6 is that it is a multi-purpose missile that can hit various targets, including ballistic missiles, aircraft, and ships. John Hill, director of the U.S. Missile Defense Agency (MDA) (Navy Major General), also stated that “The multi-purpose SM-6 missile is currently the only weapon in the U.S. arsenal capable of intercepting hypersonic weapons.”

Raytheon manufactured the SM-6 in the U.S. In the case of aircraft and ships, it can hit targets 240-460km (149.1-286 miles) away, and for ballistic missiles, it can intercept missiles flying from tens of kilometers away at a maximum altitude of 35km (21.7 miles). The length of the SM-6 is 6.55m (21.5 feet), the diameter is 34cm (13.4 inches) (booster diameter 53cm), the weight is 1506kg (3,318.5 lbs), and the maximum speed is Mach 3.5.

Intercepting all targets from the ship… ‘Patriot on the Sea’

In particular, the SM-6 is receiving attention as a key element of the U.S. Navy’s next-generation interception system. NIFC-CA (Naval Integrated Fire Control-Counter Air) is a next-generation interception system that integrates the U.S. Navy’s Aegis destroyer, E-2D Hawkeye early warning aircraft, aircraft, SM-6 missiles, etc., through a data link to enable remote combat capabilities and intercept targets beyond the horizon. That’s why it’s called the ‘Patriot of the Sea’. The SM-6 has succeeded several times in live-fire tests against various targets and is expected to be a ‘multi-player’ in the U.S. Navy’s next-generation interception system.

In this regard, the U.S. Navy set a record for the longest distance interception of an interception missile in January 2016. In July of the same year, it achieved a feat by successfully destroying a target with an SM-6 launched from a ground test facility under the guidance of an F-35B stealth aircraft equipped with an advanced multifunctional data link. It was even reported that in December of the same year, it successfully tested a sea interception against a medium-range ballistic missile with a range of 3000-4000km (1864-2485 miles). Military experts have analyzed this to demonstrate interception capabilities against China’s DF-21D and DF-26 anti-ship ballistic missiles.

A ballistic missile hits the target after going through the acceleration (ascending) stage→mid-flight stage→terminal (descending) stage after launch. Photo=Capture of ‘Nuclear Threat Prevention Global (NTI),’ a U.S. think tank

The SM-6 will primarily perform the task of intercepting North Korean ballistic missiles flying towards our military ships. It protects our Navy’s task force, composed of Aegis ships, destroyers, and military supply ships, from North Korean nuclear missile attacks.

Above all, in case of emergency, it also plays a role in defending against North Korean nuclear missile attacks targeting major infrastructure such as military command centers and nuclear power plants, along with Patriot, medium-range surface-to-air missile (M-SAM), and the Terminal High Altitude Area Defense (THAAD) system of the U.S. Forces Korea, which are ground interception systems.

However, it is well-known that the SM-6 has limited performance as a KAMD asset. According to Raytheon, the manufacturer of the SM-6, it is capable of intercepting ballistic missiles in the terminal stage. A ballistic missile hits the target after going through the acceleration (ascending) stage→mid-flight stage→terminal (descending) phase after launch. Therefore, the U.S. Terminal High Altitude Area Defense (THAAD·THAAD) system, MIM-104 Patriot, and South Korea’s Cheongung (M-SAM) intercept ballistic missiles in the terminal stage.

So, some argue that the SM-3 missile, which has superior interception capabilities than the SM-6 missile, needs to be introduced. Although the SM-6 can intercept ballistic missiles, it is virtually impossible to intercept North Korean ballistic missiles falling to the ground, such as the capital area from the sea, as the interception altitude is within tens of kilometers. It is said that the SM-6 helps intercept anti-ship ballistic missiles or supersonic cruise missiles attacking our fleet from North Korea or surrounding powers.

Moreover, when the Nodong missile is launched at a high angle, targeting the capital area from the North Korean rear base (Yeongjeo-dong base), the need for introduction is also gaining momentum due to the judgment that it is difficult to intercept with the U.S. Patriot PAC-3 missile or the domestic Cheongung-2 missile.

For this reason, some in the military argue that the SM-3 missile, which has a higher altitude interception capability, needs to be introduced to effectively respond to provocations such as North Korea’s intercontinental ballistic missile (ICBM) high-angle launch or submarine-launched ballistic missile (SLBM). The SM-3 has a maximum range of 900km (559.2 miles) and a maximum interception altitude of 500km (310.7 miles) for Block-1B. Block-2A’s maximum range is 2500km (1553.4 miles), and the interception altitude reaches 1500km (932.1 miles), making it a powerful interception missile. The U.S. and Japanese Aegis ships are known to have deployed the SM-3 improved type with a maximum interception altitude of (1200km) and 745.6 miles in actual combat.

SM-3′ Ineffective Against North Korea’s Low-Altitude Missiles

The effectiveness of the SM-3 missile defense system has come under scrutiny, as it appears ill-equipped to intercept North Korea’s low-altitude missiles, such as the KN-23, which some have likened to North Korea’s version of the Iskander missile. Unlike the high-altitude intercontinental ballistic missiles (ICBMs), these new missiles have a maximum flight altitude ranging from 35 to 60 kilometers, a significant departure from the usual trajectory.

The South Korean military had been planning to deploy the SM-3 Block-1B system, which has a minimum interception altitude of 70 to 90 kilometers. Unfortunately, these North Korean weapons fall well below the SM-3’s minimum interception altitude, rendering them incapable of intercepting these missiles and the oversized launchers they come with. The SM-3 system would only be helpful against medium-range missiles with high-angle launches, primarily aimed at the Seoul metropolitan area.

However, the need for SM-3’s utility has diminished with the development of more accurate and powerful low-altitude missiles by North Korea. Moreover, a single SM-3 missile costs 25 billion won (about US$20 million), five times that of an SM-6 missile. This poses a significant financial burden for the military. Additionally, the domestically developed long-range interceptor missile, L-SAM (with a maximum interception altitude of 40 to 60 kilometers), expected to be ready by 2024, further diminishes the effectiveness of the SM-3 system. An anonymous military source stated, “The decision to introduce SM-6 instead of SM-3 was the most rational choice considering the North’s new missile threats and cost-effectiveness.”

On the other hand, the Navy argues that both SM-3 and SM-6 systems are necessary.

A Navy spokesperson said, “SM-3 is the most effective means of intercepting high-angle launches of North Korean Nodong missiles, while SM-6 is a valuable asset for fleet air defense. The Navy believes introducing both weapon systems is the most efficient solution.” However, budget constraints present a challenge, as there is a need to prioritize weapon procurement projects. In contrast to the Defense Acquisition Program Administration (DAPA) and the Ministry of National Defense’s preference for SM-6, the Navy has advocated for SM-3 as a top priority.

By. Lee Hyun Ho