Russia appears ready to escalate its yearslong war with Ukraine, preparing tens of thousands of troops in southern Russia for what could be a new offensive with reinforcements from recently arrived North Korean troops.

Russia’s military is employing World War One-style tactics, involving relentless human wave attacks and heavy artillery, to make incremental gains in eastern Ukraine, notably around urban centers like Vuhledar.

U.S. State Department spokesperson Vedant Patel says on November 12 that the majority of some 10,000 North Korean troops sent to support Russia’s war against Ukraine are now “engaging in combat operations” in Russia’s western Kursk region.