The U.S. says there will be a "firm response" as Ukrainian forces holding ground in Russia's Kursk region now face North Korean troops "engaging in combat."

Russia attacked the Ukrainian capital Kyiv with a sophisticated combination of missiles and drones for the first time in 73 days on Wednesday, authorities reported, as the Pentagon said most of the North Korean troops sent to help Moscow’s war effort are fighting to drive Ukraine’s army off Russian soil in the Kursk border region.

North Korean soldiers, who were previously sent to Russia, are now in Kursk Oblast and are "already engaging in combat" operations against Ukraine. Source: Yonhap, citing South Korea's spy agency Details: The intelligence service reported that "North Korean soldiers dispatched to Russia have moved to Kursk Oblast over the past two weeks and their deployment to battlefields has been completed".