Kim Dong-hyun of the VOA Korean Service contributed to this report.

WASHINGTON — South Korea should integrate its missile defense system with that of the U.S. to maximize the combined capabilities to counter a potential incoming flight of North Korea’s missiles across the border, experts said in the wake of Pyongyang’s two missile launches in early May.

South Korea’s missile defense system and the U.S. antimissile defense system deployed in South Korea are coordinated but operate independently.

“The whole system would work better if it was fully integrated, if it was a completely combined operation,” said Bruce Bechtol, a former intelligence officer at the Defense Intelligence Agency who is now a professor at Angelo State University in Texas.

​Why not integrate systems?

The lack of integration is rooted in regional history. The South Korean government, whether it was conservative or liberal, never merged its system with the U.S. system for political reasons, in part, because integrating it would mean joining the U.S. missile defense alliance in the region that includes Japan, South Korea’s colonial adversary toward which South Korea’s public sentiment has been historically antagonistic, according to Bruce Bennett, a senior defense analyst at the Rand Corp. research center.

Streamlining the command and control of the two missile defense systems with autonomous command and control would cut the time needed to analyze data, share information, and cue the proper system for targeting and intercepting an incoming missile, according to David Maxwell, a former U.S. Special Forces colonel and current fellow at the Foundation for Defense of Democracies.

On May 17, the Pentagon announced the U.S. had approved a $314 million sale of air defense missiles to South Korea.

South Korea’s missile defense system, termed the Korean Air and Missile Defense (KAMD), includes Aegis and Patriot systems, and is designed to protect South Korea from missiles that fly at different altitudes and distance by detecting, tracking and intercepting incoming missiles in the air. Terminal High Altitude Area Defense (THAAD), which currently falls under the U.S. missile defense system, is also deployed in South Korea.

Aegis, a sea-based missile defense system, and THAAD are area defense weapons that have the capabilities to defend wide areas against missiles that fly high altitudes. And, the Patriot system, known as pointed defense weapons, can intercept missiles directed against smaller areas such as air base, according to Maxwell.

​No perfect defense

But they don’t provide a perfect defense that prevents missiles from getting through, he added.

“There’s no impenetrable shield,” Maxwell said. “There [is] always going to be a gap, a seam, a weakness, that the enemy is always trying to exploit and defenders are always trying to fix and find a better way. This is constantly a game of where capabilities continue to evolve.”

This was part of what was happening when North Korea tested a new missile on May 4 that is considered to be similar to the Russian Iskander, a nuclear-capable missile that flies lower than the short-range ballistic missiles North Korea tested before.

“A ballistic missile leaves the earth’s atmosphere and glides back down,” Bechtol said. “This [test] missile does not, as far as I can tell, leave the Earth’s atmosphere. It operates more like a cruise missile than a ballistic missile.”

A cruise missile flies on a relatively straight line and at a lower altitude than a ballistic missile, which arcs up before curving down toward a target.

​Russian-like missile poses challenges

Experts said if the new missile is modeled after the Iskander, it could pose multiple challenges and could exploit gaps in the existing missile-defense coverage in South Korea. 

The new missile’s “flattened flight path” toward a target “makes it difficult to intercept” with current defense systems, said Michael Elleman, a senior fellow at the International Institute for Strategic Studies.

The North Korean version of the Iskander does not fly higher than 50 kilometers and can travel a ground distance as far as 280 kilometers, according to Elleman.

But THAAD and the Aegis SM-3 interceptor operate at an altitude above 50 kilometers, and the Patriot system’s effective intercepting range is at an altitude of about 25 to 30 kilometers with the Patriot variant PAC-3 Missile Segment Enhancement (MSE) interceptor extending its flight to an altitude of about 40 kilometers.

That leaves “a gap in interceptor coverage” of at least 10 kilometers between the missile defense systems that operate at roughly 40 to 50 kilometers, said Ellemen. “The Iskander spends most of its flight path in this gap, making it difficult to intercept.”

The Iskander can fly at a high speed, presenting another challenge for the current missile defense system.

Bennett said, “The Iskander flies perhaps 20-25 percent faster than the Scud,” a series of tactical ballistic missiles that could travel five times the speed of sound, potentially capable of reaching South Korea in about five minutes, Bennett said.

“THAAD and the SM-3 on the Aegis [equipped] ships should be able to handle this speed. [But] the Iskander flies low, [a] potential challenge for THAAD and the SM-3,” he added.

Most accurate North Korean missile

The Iskander can be mounted on mobile launch platforms, meaning it can be moved and fired quickly.

“It’s a solid fuel missile,” Bechtol said, explaining that the fuel can be loaded ahead of launch “and moved much more quickly than liquid-fuel missiles.” The latter need fueling just before launch.

The Iskander’s maneuverability also makes it difficult for THAAD, Aegis SM-3, and the Patriot system to intercept.

“The Iskander has fins mounted at the back of the missile, which allow it to maneuver during the entire flight,” Ellemen explained. “This makes it much more difficult to predict an intercept location and launches the interceptor on the optimal path for an engagement resulting in destruction of the threat.”

Bechtol said, “It would be the most accurate missile the North Koreans have ever had, so accurate that they could actually fire out … [and] target barracks, flight lines for aircraft, headquarter buildings.”

With the missile test, “the North Koreans are showing us that they have a missile [with which] they can accurately target Osan Air Base or Camp Humphreys in a very real, in a very dangerous way,” Bechtol said, citing American installations in South Korea.

“They were able to keep in accordance with the agreement they made with [President Donald] Trump, and at the same time, threaten the United States and South Korea in a very compelling way,” he added.

When the Pyongyang government began talks with Washington last year, it pledged to suspend nuclear and long-range missile tests.

​Complicated political situation

Merging South Korean and U.S. missile defense systems could be hampered by the political situation in South Korea, according to Maxwell. Public attitudes have changed little since 2017, when hundreds of South Korean citizens protested the installation of THAAD at a U.S. military south of Seoul.

“I just don’t see the political will for that in South Korea among majority of the people or the current rule and government,” Maxwell said.

Bennett said a North Korean missile that slipped under defense systems could devastate the peninsula, depending on the type of warhead it carried, “… which in theory could be conventional, nuclear or chemical,” he said. “So the defense would turn to passive defense: protecting people in shelters with masks and protective clothing.”

According to Maxwell, a variant of the Patriot interceptor, the PACT 3 Guidance Enhanced Missile (GEM-T) under the U.S. missile defense system in South Korea is better able “to defeat tactical ballistic missiles and aircraft and cruise missiles” and could potentially intercept the new kind of missile North Korea tested.
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