Ukraine is facing a ‘hammer blow’ of 50,000 Russian troops in Kursk – can they hold out? - IN DEPTH: Experts tell Andy Gregory and Tom Watling that the real question is how much Kyiv’s troops are able

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

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."