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."

Ukrainian President Volodymyr Zelensky said Russia has deployed nearly 50,000 troops to Kursk, the southern Russian region where Kyiv launched its surprise counteroffensive in the summer.

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 have engaged in combat operations against Ukraine alongside their Russian allies, South Korea's spy agency said on Wednesday. Seoul's confirmation comes amid growing global criticism as the two countries strengthen military ties,

Russia has amassed a large force of tens of thousands — including recently arrived North Korean troops — to carry out an assault on the Ukrainian positions in Russia’s Kursk region expected in the coming days,

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".

North Korean troops could be thrown into the meatgrinder that is Russia's war in Ukraine, with 10,000 already deployed according to US intelligence services with more feared

The deployment of around 10,000 North Korean troops in Russia's border Kursk region is convincing the Pentagon to see the conflict in a wider context