Kim says new engines mark ‘strategic shift’ in North’s nuclear forces, ICBM test possible next month

North Korean leader Kim Jong-un said on September 8 that the country’s development of a high-thrust solid-fuel engine using new materials signals a “strategic shift” in strengthening its nuclear forces.

The announcement has sparked speculation that Pyongyang may test-fire its new intercontinental ballistic missile (ICBM), the Hwasong-20, or a submarine-launched ballistic missile (SLBM) around Oct. 10, the 80th anniversary of the founding of the ruling Workers’ Party.

Kim observed a “ground jet test of high-thrust solid-fuel engine using the composite carbon fiber material” conducted jointly by the Missile Administration and Academy of Chemical Materials on September 8, according to the state-run Korean Central News Agency (KCNA) on September 9.

A spokesperson for the Missile Administration said this ninth test marked “the last one in the development process,” suggesting that the engine is ready for deployment.

Kim described the development of the carbon fiber-based engine as “the success assuming the most strategic nature in the recent modernization of defense technology and heralds a significant change in expanding and strengthening the nuclear strategic forces” of North Korea.

Observers say Kim’s remarks indicate a substantial improvement in ICBM propulsion technology. The announcement was timed to coincide with the North’s Sept. 9 Foundation Day, likely intended to showcase the completion of a lightweight, high-efficiency solid-fuel engine to external audiences.

Notably, KCNA, which caters to international audiences, revealed that the engine’s maximum thrust reached 1,971 kilonewtons (kN), surpassing the 1,960 kN figure disclosed when the engine was unveiled on Sept. 2 — just a day before Kim attended China’s Victory Day celebrations.

Lee Chun-geun, a propulsion system expert and a guest researcher at South Korea’s Science and Technology Policy Institute, noted that “heat-resistant materials used in the nozzle throat of solid engines are the biggest bottleneck in developing high-thrust engines.” He added that by developing high-performance carbon fiber composites capable of withstanding extreme heat during extended burn times, North Korea is signaling its acquisition of an advanced, high-difficulty technology.

However, Lee cautioned against overinterpreting the significance of the thrust data alone. “To accurately assess the engine’s performance, the duration of sustained thrust is critical,” he said.

Experts view the test as part of a broader strategy following Kim’s appearance at China’s Victory Day military parade, where he emphasized trilateral solidarity with China and Russia and is now showcasing improved ICBM capabilities that could reach the U.S. mainland. Kim’s decision to make his first public appearance after returning from China at the engine test site lends credence to this interpretation.

“North Korea revealed the warhead of what is believed to be the new multiple-warhead Hwasong-20 ICBM on September 2, and is now unveiling its high-thrust solid-fuel engine,” said the conservative People Power Party Rep. Yu Yong-weon, a member of the National Defense Committee. “This is a classic example of its salami-slicing strategy to escalate tensions.”

He added, “A test launch of the new ICBM around Oct. 10 is plausible.”

Some analysts speculate that because the new high-thrust engine is compact and lightweight, it could eventually be used for SLBMs or the stalled development of military reconnaissance satellite launch vehicles.

BY LEE YU-JUNG,CHUNG YEONG-GYO,SHIM SEOK-YONG [kim.minyoung5@joongang.co.kr]