North Korean leader Kim Jong Un oversaw a ground test of a newly upgraded high-thrust solid-fuel engine designed for missiles capable of striking the U.S. mainland, state media reported Sunday. The Korean Central News Agency announced the test, which involved a carbon-fiber composite engine producing a maximum thrust of 2,500 kilonewtons, an upgrade from previous models around 1,970 kilonewtons.

Kim hailed the development as having "great significance in putting the country’s strategic military muscle on the highest level," according to KCNA. He described it as a key boost to North Korea's strategic military capability amid a five-year defense plan to modernize its arsenal of nuclear-capable ballistic missiles. The engine is intended for intercontinental ballistic missiles, or ICBMs, enhancing their range and payload potential.

Experts note that solid-fuel engines offer significant advantages over liquid-fuel predecessors. They allow for quicker launches, easier mobility on land-based trucks or submarines, and reduced detectability before firing, as no on-site fueling is required. The increased thrust could enable smaller ICBMs or multiple independently targetable reentry vehicles, or MIRVs, designed to overwhelm U.S. missile defenses. North Korea has conducted several ICBM tests in recent years, demonstrating potential reach to the continental United States.

The test aligns with Pyongyang's accelerated weapons program despite international sanctions. It follows a series of demonstrations this year, including hypersonic missile firings in January, multiple ballistic missile launches in March, and strategic cruise missile tests. Kim recently accused the United States of "global state terrorism and aggression" in a parliamentary speech, referencing Middle East conflicts, while leaving room for dialogue with President Donald Trump, absent demands for denuclearization.

South Korea and the United States are closely monitoring the activity, according to reports. No immediate condemnations emerged early Sunday, though the test heightens tensions on the Korean Peninsula. Analysts caution that while North Korea's claims advance its missile technology, challenges remain, such as warhead reentry survivability during full ICBM flights. Some question if announcements exaggerate progress for propaganda.

The demonstration underscores Kim's commitment to nuclear deterrence, complicating diplomatic efforts stalled since the 2019 summits. Possible Russian technical assistance has been speculated amid deepening ties between the two nations.