Russia battled on Sunday to drive the last Ukrainian soldiers from western Russia, Russian officials said, after a seven-month incursion by Ukraine that aimed to distract Moscow's forces, gain a bargaining chip and rile President Vladimir Putin.

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.

Russian forces have begun an assault on the town of Sudzha, the main population center in the Kursk region that was captured by Ukraine last year, a top Russian commander said on Tuesday. The advance puts Moscow on the verge of ending the first invasion of Russian territory since World War II.