Referenews

On Thursday, Mr. Kim oversaw the test of a “high-thrust solid-propellant motor” that state media championed as part of a new strategic-weapons system. State-media photos published Friday showed Mr. Kim holding a cigarette and smiling in front of a cloud of smoke at the Sohae rocket-launch site. Other images showed flames shooting out from a large, black engine placed on a horizontal test stand. 

North Korea has launched dozens of solid-fueled, short-range ballistic missiles this year, designed to evade and penetrate U.S. and allied missile defenses. But the Kim regime’s intercontinental ballistic missiles, which have shown the ability to reach the U.S. mainland, are liquid-fueled.

Developing a solid-fuel ICBM that can be launched from both land and sea is one of Mr. Kim’s prominent goals for a five-year weapons strategy that he announced in January 2021.

The threat of the Kim regime’s nuclear program is becoming more real as the solid-fuel rocket engine is aimed at advancing its missiles to possess speed and covertness to evade Washington’s missile defenses, said Yang Moo-jin, president of the University of North Korean Studies in Seoul.

“Further engine tests will lead to testing solid-fuel ICBMs, which puts even more pressure on the U.S. and South Korea in countering North Korea’s threat,” Mr. Yang said.

North Korea has conducted an unprecedented number of ballistic-missile launches this year. U.S. and South Korean officials have said the North has completed preparations to conduct its seventh nuclear test, which would be the nation’s first since 2017. This year, North Korea test-fired the Hwasong-17, which is believed to be the largest road-mobile, liquid-fueled ICBM in the world.

Liquid propellants are highly corrosive and volatile, and aren’t able to be stored in a missile for long periods. Solid-propellant rockets use fuel less prone to leaking corrosive vapor and are designed to store the fuel inside the missile, making them faster to deploy.

In the aftermath of Thursday’s engine test, Mr. Kim said the country would pursue “another new strategic weapon” in the shortest span of time. The 38-year-old dictator praised officials for solving an important problem in achieving the tasks presented under the country’s weapons-development plan, according to state media. Mr. Kim didn’t specify what the weapon would be.

The engine tested on Thursday could eventually be used for North Korea’s ICBMs or submarine-launched ballistic missiles to deliver a nuclear warhead to the U.S. mainland, weapons experts say. The engine test, which reportedly had a high thrust of 140 ton-force, is the first step to building a solid-propellant ICBM, but the experts note that North Korea still faces hurdles in getting from a ground test to deploying such a weapon.

Typically countries test the engine motor multiple times before testing it in ICBM configuration, but it is unclear how far along North Korea is in building a long-range solid-fuel rocket.

North Korea said it conducted an engine test in December 2019 at the Sohae facility but didn’t provide any additional information or photographs from the test site. In August, analysts said North Korea appeared to have conducted an engine test, citing destruction of trees near the Sohae launch station as observed in satellite imagery. But neither South Korea’s military nor North Korean state media have confirmed the test.

Major reconstruction has been continuing at the Sohae facility since Mr. Kim’s visit in March when he ordered upgrades including expanding the capacity of the engine-test stand. Satellite imagery showed construction of a horizontal-engine test stand, placed to expand testing capabilities at the Sohae launching station, according to a Thursday report by the Center for Strategic and International Studies, a Washington-based think tank.

North Korea built the test stand for larger solid-fuel rockets in less than a month, then tested the rocket engine shortly after, indicating the country has been working on developing long-range solid-fuel rockets for a while to catch up to modern militaries, said David Schmerler, a senior research associate at the James Martin Center for Nonproliferation Studies.

“This would be North Korea’s biggest solid-fuel test ever conducted,” Mr. Schmerler said. “Eventually it will increase the survivability of its missiles.”

North Korea’s engine test came as International Atomic Energy Agency chief

Rafael Grossi

visited South Korea this week, vowing an all-out effort to halt North Korea’s nuclear program. On Thursday, South Korean President

Yoon Suk

-yeol met with Mr. Grossi, expressing concern over Pyongyang’s race to advance its nuclear and missile program and calling on the agency to help deter North Korea from provocations.

Write to Dasl Yoon at dasl.yoon@wsj.com