The Ukrainian army is advancing in attacks near the eastern city of Bakhmut, Ukrainian commanders said Friday, in fighting that has shifted the front line only slightly but is exposing fissures, confusion and alarm among Russia’s forces in the war.

Russia’s pro-war bloggers were quick to claim that Ukraine’s long-anticipated counteroffensive had begun, but Ukrainian officials downplayed the advances and described them in more local terms. Ukrainian soldiers broke through Russian lines south of Bakhmut on Wednesday, they said, and then exploited that breach, assaulting Russian forces near the city and threatening Russian flanks to the north and south.

A video that appears to have been posted first by the Ukrainian news outlet Channel 24, which said it was provided by Ukraine’s 77th Airmobile Brigade, showed parts of northern Bakhmut on fire Friday evening.