[News Terms] US Approves Sale of Interceptor Missile 'SM-6' to Korea

The 'SM(Standard Missile)-6' is a ship-based air defense missile operated by the U.S. Navy with a range of 240 to 460 km. It is equipped with an active guidance system that allows it to directly track targets using its own radar without support from the launching ship's target acquisition radar, significantly enhancing the ship's ability to engage multiple targets simultaneously and greatly improving simultaneous engagement capabilities.

The SM-6 missile is a long-range ship-based air defense missile developed by Raytheon in the U.S. that can intercept enemy aircraft before they launch anti-ship missiles. It was developed by significantly upgrading the SM-2 ship-based air defense missile, which has a range of 170 km, to expand the fleet's air defense coverage. The U.S. military operates the high-performance interceptor missile 'SM series' as part of its Ballistic Missile Defense (BMD) program.

The Republic of Korea Navy Eulji Mundeok-class ship is firing the Sea-Sparrow surface-to-air guided missile in the West Sea.
[Photo by Asia Economy DB]

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The U.S. military operates missiles ranging from the older SM-1, deployed mainly in the 1960s to 1980s with a range within 100 km, up to the SM-6. The SM-2, deployed since the late 1970s, started as a long-range interceptor system based on large cruisers. With a range of around 200 km, it supports the Aegis system and is currently the missile operation system of the Republic of Korea Navy. The SM-3 is the most powerful ballistic missile defense system currently in operation. It has a range of 900 to 2,500 km and an interception altitude of 500 km, covering even outer space. It can intercept intercontinental ballistic missiles (ICBMs) and can also be used to destroy malfunctioning or end-of-life satellites in orbit.

The SM-3 uses an infrared sensor on its warhead to locate the target missile and directly hit it with kinetic energy. The warhead controls its attitude using gas thrusters mounted on its sides as it flies toward the target. Because it is a missile focused on intercepting high-altitude ballistic missiles, it cannot operate within the atmosphere. Therefore, the U.S. Army operates THAAD (Terminal High Altitude Area Defense) and PAC-3 for high-altitude missile defense, while the Navy operates SM-2 and SM-6 for low to medium altitude air defense.

At one point, the Republic of Korea Navy considered acquiring the SM-3 but rejected it due to it being 'over-spec' and too expensive. THAAD's maximum speed exceeds Mach 8.2, SM-2 ranges from Mach 10 to 18, and SM-6 is around Mach 3.5 to 4.1. The U.S. military operates the SM-3 missile to attempt a first interception at high altitude, and if that fails, it tries a lower-tier defense with the SM-6 missile. The SM-3 Block 1B missile costs about 25 billion KRW per unit, while the SM-6 costs around 5 billion KRW per unit.

However, the slower speed of the SM-6 raises concerns regarding North Korea. It is questionable whether the SM-6 missile launched from our Aegis ships can intercept North Korea's new tactical missile (KN-23), which is more than twice as fast. For this reason, there are arguments that the SM-3 should be introduced instead of the SM-6.

KDX-Ⅲ No.1 ship, ROKS Sejong the Great.
Photo by Asia Economy DB

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On the 14th (local time), the U.S. government provisionally approved the sale of SM-6 ship-based air defense missiles to South Korea through the Foreign Military Sales (FMS) program. The Defense Security Cooperation Agency (DSCA) under the U.S. Department of Defense announced that the State Department approved South Korea's request to purchase SM-6 missiles and related equipment worth $650 million (approximately 850 billion KRW).

The final sale will be executed after congressional approval, which is expected to proceed without significant issues. The South Korean government requested to purchase up to 38 SM-6 missiles. The SM-6 is planned to be installed on three Jeongjo Daewang-class destroyers equipped with BMD capabilities. The South Korean government views the SM-6 as capable of intercepting aircraft, ballistic missiles, and cruise missiles, enabling a denser maritime air defense network and significantly enhancing the ability to respond to North Korean cruise and ballistic missiles. The U.S. also sold SM-6 missiles to Japan last year.

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