As the war in Ukraine approaches its 100th day, President Volodymyr Zelenskyy said Thursday that Russian forces now control one-fifth of the country, a blunt acknowledgment of the slow but substantial gains that Moscow has made in recent weeks.

Though battered, depleted and repulsed from their initial drive to capture the Ukrainian capital of Kyiv, Russian troops have used their superior artillery power to grind closer to their goal of taking over the eastern regions of Luhansk and Donetsk, known collectively as the Donbas, where Kremlin-backed separatists have been fighting Ukrainian troops since 2014.

Zelenskyy said Russia had expanded its control of Ukrainian territory from an area roughly the size of the Netherlands before the invasion began Feb. 24 to an area now greater than the Netherlands, Belgium and Luxembourg combined. Seizing that swath of land could give Russian President Vladimir Putin huge leverage in any future talks to end the war, as well as a base of operations to launch further attacks inside Ukraine.