North Korean leader Kim Jong Un oversaw testing of a new high-thrust solid-fuel rocket engine made with carbon-fiber materials, according to state media reports.
The engine produced 2,500 kilonewtons of thrust, exceeding last year's test performance. Analysts say such engines could support more mobile long-range missiles capable of striking the US mainland.
Kim declared the test had "great significance in putting the country's strategic military muscle on the highest level." The advancement fits North Korea's five-year defense plan to upgrade strategic strike capabilities.
Solid-fuel systems enable faster launches with less warning than older liquid-fuel missiles, making them harder to detect. Pyongyang still faces technical barriers before deploying fully reliable intercontinental ballistic missiles.
Since diplomatic breakdown with Donald Trump in 2019, North Korea has accelerated nuclear and missile development despite international sanctions.