US officials have claimed that North Korea is suffering mass casualties on the front lines of Russia’s war against Ukraine, being used in costly “human wave” attacks. White House spokesperson John Kirby told reporters on Friday that thousands of North Korean troops had been killed or wounded in the last week alone.

There are risks of North Korea sending additional troops and military equipment to the Russian army,” Zelensky said. “We will have tangible responses to this.”

Despite their elite status, North Korea's "Storm" troops were ill-prepared for the war, South Korea's National Intelligence Service said.