North Korea's Kim Jong Un oversees test of new rocket engine for ICBMs

North Korea said Tuesday that leader Kim Jong Un supervised a test of a new rocket engine designed for intercontinental ballistic missiles, the latest step in his effort to build an arsenal that poses a viable threat to the continental United States.

North Korea's official Korean Central News Agency said Monday's event marked the ninth and final ground test of the solid-fuel rocket engine built with carbon fibre and capable of producing 1,971 kilonewtons of thrust, more powerful than past models.

The report came a week after Kim visited the research institute that developed the engine, which North Korea then said will be used for future ICBMs, including a system called Hwasong-20.

North Korea in recent years has flight-tested a variety of ICBMs that demonstrated potential range to reach the US mainland, including those with built-in solid propellants that are easier to move and conceal and can be prepared for launch more quickly than the North's previous liquid-fuel missiles.

Kim has called for further advancements in North Korea's long-range weapons, including the development of multi-warhead systems that would improve their chances of defeating missile defences.

All of North Korea's ICBM tests so far have been conducted at steeper-than-normal trajectories to avoid neighbouring territories, and experts say the country may not yet have perfected the technology needed to ensure its warheads survive the harsh conditions of atmospheric re-entry.

KCNA said Kim expressed satisfaction after Monday's test, calling the eye-opening development of the new rocket engine a significant change in his effort to expand North Korea's nuclear forces.

Kim has stepped up testing activities since the collapse of nuclear talks with the US in 2019 under President Donald Trump's first term, demonstrating weapons of various ranges designed to strike US allies in Asia and the US mainland.

Analysts say Kim's nuclear push is aimed at eventually pressuring Washington to accept the idea of the North as a nuclear power and to negotiate economic and security concessions from a position of strength.

Kim is also trying to bolster his leverage by strengthening his cooperation with traditional allies Russia and China, in an emerging partnership aimed at undercutting US influence.

Kim has sent thousands of troops and large quantities of military equipment to Russia to help fuel President Vladimir Putin's war on Ukraine. He visited Beijing last week, sharing the spotlight with Chinese President Xi Jinping and Putin at a massive military parade marking the 80th anniversary of the end of World War II and China's fight against Japanese aggression. Experts say Kim's rare foreign trip was likely intended to boost his leverage ahead of a potential resumption of talks with the United States.

In a separate report, KCNA said Xi sent a letter to Kim on North Korea's founding anniversary, which fell on Tuesday, and called for strengthened strategic communication between the countries.