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North Korea’s state-run Korean Central News Agency reported on Jan. 15 that the North had successfully test-fired a hypersonic, solid-fuel IRBM. (KCNA/Yonhap)

North Korea claimed on Monday that it had successfully test-fired an intermediate-range solid-fuel ballistic missile it said was equipped with a hypersonic warhead on Sunday. 
 
As this is the first time the North has fired a hypersonic IRBM using solid fuel, this development is predicted to test the limits of South Korea’s three-axis system for responding to North Korean nuclear and missile threats, as well as the US and Japan’s joint missile defense system.
 
“The test-fire never affected the security of any neighbouring country and had nothing to do with the regional situation,” a Monday article in North Korea’s Workers’ Party of Korea-run Rodong Sinmun read. “The Missile Administration explained that the test is a part of regular activities of the administration and its affiliated defence science institutes for developing powerful weapon systems.”
 
However, the North revealed no specifics of the missile’s altitude or of its trajectory. IRBMs can fly from 3,000 to 5,500 kilometers, which means that a launch from Pyongyang would put locations like Okinawa, which is home to many US military bases, and Guam, where US military strategic assets such as B-52 bombers are stationed, within striking range.
 
North Korea has flight-tested hypersonic IRBMs before, once in September 2021 and once in January 2022, but utilized liquid fuel in both cases.
 
Solid-propellant missiles are harder to detect than liquid-fuel missiles, which require plenty of time for fueling ahead of launch. This limits the ability of South Korea, the US and Japan to respond to launches of solid-fuel missiles.
 
Despite North Korea’s claims that the launch was part of “regular activities” for the development of weapons and was irrelevant to the regional situation, the nature of the missile prompted Seoul’s Ministry of Defense to put out a statement. 

“Our military is enhancing its ability to implement integrated extended deterrence with the US, as well as strengthening South Korea’s independent three-axis response system. If North Korea deliberately provokes us, we will be swift, forceful and definitive in our response,” the statement read. 
 
The hypersonic aspect of this weapon does not actually mean much. A hypersonic speech is one that exceeds Mach 5 — five times the speed of sound. Most regular short-range ballistic missiles fly at speeds faster than Mach 5. In fact, where speed is concerned, a hypersonic missile is slower than the average ballistic missile as the warhead separates after the boost phase and flies through the atmosphere with air resistance.
 
However, the irregularity of its maneuvers is what makes some concerned that this will change the paradigm of security on the Korean Peninsula. By stating that this missile was loaded with a “manoeuvrable controlled warhead,” North Korea is announcing that the missile could be maneuvered in ways that make it hard to track or eliminate. 
 
The average ballistic missile’s trajectory is that of a parabola, which makes it easy to predict where it will make impact once the missile’s initial direction and speed are gauged. However, a ballistic missile with maneuvering characteristics will be able to conduct erratic maneuvers at low altitudes in its terminal phase, making it difficult to discern the point of impact.
 
For instance, if the flight distance of a hypersonic missile is 1,000 kilometers, it will rise for 600 km or so after launch and its trajectory will be the same as a regular ballistic missile, making it easy for South Korea to detect it with existing radars.
 
However, once it leaves the Korean Peninsula and reaches a flight distance of 600 kilometers or more, it will begin its maneuvers at a low altitude of around 50 kilometers, making it difficult for either the US or Japan to detect.
 
This explains why South Korea determined that the flight distance of North Korea’s missile was 1,000 kilometers, while Japan’s Defense Ministry declared that it would have been at least 500 kilometers on Sunday.
 
This also means that there will be disparities in the responses carried out by South Korea, the US and Japan.
 
“While it is true that detecting and intercepting North Korean hypersonic ballistic missiles will be difficult with existing anti-aircraft weapons, South Korea is capable of detecting and intercepting them, so it is difficult to say that this is a ‘game changer’ in a war scenario,” assessed Shin Seung-ki, a researcher at the Korea Institute for Defense Analyses. 
 
On Sunday night, the special envoys for North Korea issues of South Korea and Japan — Kim Gunn and Hiroyuki Namazu, respectively — and the US deputy special envoy, Jung Pak, held a trilateral call to share assessments on North Korea’s launch of the IRBM, and talked about closely coordinated responses among the three countries.
 
The three representatives condemned North Korea’s first missile launch of 2024, which came in addition to its live-fire drills along its western coast, as a breach of UN Security Council Resolutions and underscored that Pyongyang’s actions destabilized regional and international security.
 
By Kwon Hyuk-chul, staff reporter; Lee Je-hun, senior staff writer

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