WASHINGTON - National security advisers for the US, South Korea and Japan expressed "grave concern" on Oct 25 over the deployment of North Korean troops in Russia for possible use against Ukraine, the White House said.

       The trio see the North Korean troop presence as the latest sign of growing Moscow-Pyongyang military ties, and they called on Russia and North Korea to cease arms and missile transfers, White House national security spokesman John Kirby told reporters.

       The transfers violate UN Security Council resolutions, he said.

       Mr Kirby briefed reporters after US national security adviser Jake Sullivan held talks in Washington with his South Korean and Japanese counterparts, Mr Shin Won-sik and Mr Takeo Akiba, respectively.

       "The national security advisers express grave concern over troop deployments" by North Korea in Russia, "potentially for use against Ukraine," Mr Kirby said.

       The North Koreans' presence in Russia and the weapons transfers "expand the security implications of Russia's brutal and illegal war beyond Europe and into the Indo-Pacific," he added.

       Russian President Vladimir Putin on Oct 24 did not deny that North Korean troops are in Russia. But he said it was Moscow's business how to implement a treaty with Pyongyang that includes a mutual defense clause to aid each other against external aggression.

       Mr Kirby spoke after Ukrainian President Volodymyr Zelensky, citing intelligence reports, said on X that Russia plans to deploy North Korean troops beginning on Oct 27.

       He did not say where they would be sent.

       Ukrainian military intelligence on Oct 24 said that around 12,000 North Korean troops, including 500 officers and three generals, were already in Russia, and training was taking place on five military bases.

       Mr Kirby said it is possible that there are more than 3,000 North Korean soldiers in Russia, the size of the deployment he gave on Oct 24.

       "We are looking into reports that the number could be north of that," he said.

       Some North Korean troops could be sent to fight Ukrainian forces that have been holding a chunk of Russia's Kursk region since August, Mr Kirby said.

       Russia launched its full-scale invasion of Ukraine in February 2022. REUTERS