North Korean troops have now entered Russia’s war with Ukraine in a major way, and some have been killed, Western officials say.

White House National Security communications adviser John Kirby said Russia was treating North Korean troops as “expendable” by sending them on impractical ground operations in its war against Ukraine.

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.”

North Korea is preparing to deploy additional troops and weapons, including kamikaze drones, to aid Russia in its full-scale war against Ukraine, the South Korean military said on Dec. 23.

In one week there were more than a thousand North Koreans casualties in the fight with Russia against Ukraine. U.S. officials say they are sent into battle with little equipment or preparation.

Ukrainian President Volodymyr Zelenskiy has reported significant battlefield losses among North Korean troops fighting in Ukraine, claiming they are left unprotected by Russian forces. The statement sheds light on the challenges faced by foreign troops supporting Russia in the conflict and raises questions about the treatment and coordination of allied forces on the front lines.