Since then, Russian forces – bolstered by thousands of North Korean troops sent by Putin-ally Kim Jong-un – have sought to claw back most of that land. The North Korean troops began arriving in Kursk from late October as part of a mutual defence pact agreed between Putin and Kim.

Russia’s president, Vladimir V. Putin, dressed in fatigues, visited a command post near the front in Kursk late Wednesday to cheer on his military’s ejection of Ukrainian forces from much of the territory they had been occupying in the Russian border region.

Russia said on Thursday there was no doubt that its troops would soon complete the task of clearing out Ukrainian forces from Russia's Kursk region where they have held a pocket of territory for more than seven months.