On Feb. 25, an elite Russian drone group—the Rubicon Center of Advanced Unmanned Systems—launched a devastating wave of attacks on the main supply line supporting the Ukrainian garrison in Sudzha, the center of the Ukrainian-held salient in western Russia’s Kursk Oblast.

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.

President Zelenskiy said his troops in Kursk were not surrounded, but said there might be a new Russian attack on Ukraine's northeastern Sumy region.