North Korea announced it is building its first nuclear-powered submarine, marking its latest effort to strengthen military leverage over the West after diplomatic relations between Washington D.C. and Pyongyang soured following a failed 2019 summit.

Leader Kim Jong Un is aiming to increase North Korea’s nuclear weapons capability as the U.S. remains cautious about the country’s alliance with Russia during the Ukraine war. North Korea has reinforced Russia with thousands of soldiers in its fight against Ukraine.