Ukraine’s President Volodymyr Zelenskyy said that fighting is severe in Severodonetsk, the epicenter of the conflict in eastern Ukraine.

Russian and Ukrainian forces in the city — the last stronghold of Ukraine in the Luhansk province — are fighting for “literally every meter,” he said.

Russian troops have tried to encircle and seize Severodonetsk for some time. Losing the city would be a major blow for Ukraine.