South Korea Dismisses North Korean Missile Chief’s Doubts Over Its First Hypersonic Glide Vehicle Test

South Korea’s defence ministry has rejected a claim by North Korea’s missile chief that the country’s first hypersonic glide vehicle, test fired on October 8 with President Lee Jae Myung watching, may never have reached hypersonic speed. Jang Chang-ha, director general of the North Korean Missile Administration, told the state news agency KCNA on October 15 that photographs released by Seoul showed the vehicle plunging into the sea “not stained with any soot” and with its paint still clean. The ministry responded the same day that advanced thermal protection makes visible soot impossible during hypersonic flight, and said the military would further develop the technologies needed to weaponise the glider. The exchange highlights how little Seoul has disclosed, with no figure published for the vehicle’s speed or range.

The test was conducted by the state-run Agency for Defense Development, reportedly from a barge off its Anheung test centre in Taean around 130 kilometres south of Seoul. Presidential spokesperson Kang Yu-jung stated that evening that the glider separated from its booster at its target altitude and flew its planned path, manoeuvring horizontally and vertically at low altitude before striking its target. The launch was intended to verify ultra high temperature thermal protection materials, guidance and control, and irregular flight at low altitude. President Lee, who inspected a Hyunmoo-5 heavy ballistic missile launcher on the same day, told the development team that “we must not rest on today’s success.” The test followed a landmine explosion on the South Korean side of the Military Demarcation Line on September 21, which Seoul has blamed on North Korean troops and Pyongyang denies.

The jibe comes from a state whose own hypersonic claims Seoul has repeatedly disputed. North Korea first claimed a glide vehicle test with the Hwasong-8 in September 2021, and on January 6, 2025 KCNA claimed a new intermediate range missile had flown 1,500 kilometres at Mach 12, which the South Korean Joint Chiefs of Staff called likely deception after tracking a flight of around 1,100 kilometres. On October 3 the South Korean military assessed a 700 kilometre flight that Pyongyang put at 1,000 kilometres. North Korea has also fired two types of strategic cruise missiles from a submarine in the same week, and with five years of hypersonic testing behind it remains considerably ahead of the South, whose industry is better known for winning tank orders abroad.

Glide vehicles are lifted by a ballistic missile booster before separating and gliding at speeds above Mach 5, manoeuvring inside the atmosphere to complicate interception by layered missile defences built around predictable trajectories. Sustained flight at these speeds heats the vehicle’s skin to well over 1,000 degrees Celsius, which is why thermal protection headed Seoul’s list of test objectives. Protection systems broadly divide into ablative coatings, which char as they carry heat away, and non-ablative carbon and ceramic composites designed to survive without significant surface loss, and Seoul has not stated which approach its vehicle uses. South Korea’s strike arsenal currently rests on the Hyunmoo ballistic missile family, the newest of which, the Hyunmoo-5, entered service around the end of 2025 with a warhead reported at around eight tonnes.