The daring campaign Ukraine launched last summer to seize and occupy Russian territory appears to be nearing an end.

A Russian service member walks past destroyed buildings in the town of Sudzha, which was recently retaken by Russia's armed forces in the course of Russia-Ukraine conflict in the Kursk region, Russia,

The BBC has received extensive accounts from Ukrainian troops, who recount a "catastrophic" withdrawal in the face of heavy fire, and columns of military equipment destroyed and constant attacks from swarms of Russian drones.

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.

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.

President Volodymyr Zelensky said that Ukrainian troops have not been encircled by Russian forces in Kursk region, accusing Russian leader Vladimir Putin of “lying” about the situation on the ground.