At the height of the campaign, Ukrainian forces controlled some 500 square miles of Russian territory. Now they hold just a small sliver of land along the border.

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.

Ukrainian troops are still fending off Russian and North Korean forces in the Kursk region but face a potential new attack on Ukraine's northeast Sumy region, President Volodymyr Zelenskiy said on Saturday.