KYIV (Reuters) -Ukrainian forces have stopped Russian troops advancing in the northeastern Sumy region and are now battling to regain control along the border with Russia, President Volodymyr Zelenskiy said.

It’s the first time in three years of war that Russian troops have entered the Dnipropetrovsk region, a sign of battlefield momentum.

Seizing complete control of the region − nearly one-third of which remains under Ukrainian control − has been a primary goal for the Kremlin. The arrival of summer has made it easier for Russian forces to advance.