Eugene Spector, who was already serving a 3½-year sentence in Russia for bribery, received the additional sentence after being charged with espionage last year.

Ukrainian President Volodymyr Zelenskiy said on Monday that more than 3,000 North Korean soldiers have been killed and wounded in Russia's Kursk region and warned that Pyongyang could send more personnel and equipment for Moscow's army.

As the war in Ukraine drags on toward a fourth year, North Korea is preparing to send Moscow more troops beyond the 12,000 already there, as well as additional weapons, including suicide drones, according to the latest assessment from South Korean intelligence.