Russian armed forces were trying to break through Ukrainian defense lines in Ukraine’s northeast on Wednesday, Ukrainian officials said, a sign of building Russian pressure across the front.

Serhiy Haidai, governor of Ukraine’s eastern Luhansk province, said the number of Russian attacks around the city of Kreminna, long a target for Ukrainian troops, had soared. Russian forces were also assaulting Bilohorivka, he said, a much-contested village to the south of Kreminna.