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.

President Vladimir Putin said on Thursday that Russia had trapped the remaining Ukrainian soldiers in its western Kursk region, where they have clung on for more than seven months in one of the key battles of the war.