Analysis: Ukraine, Russia set stage for climax of Battle of Donbas

As Russia intensified its war effort against Ukraine, the battles in Ukraine's Donbas region faded from international focus. However, the fighting in the east remains intense and brutal, with both sides trying to get an upper hand before winter. In 2026, Ukraine has seen relative success on the front line, with net Russian territorial gains plateauing despite heavy casualties.

Ukrainian forces also conducted two successful counterattacks, each with strategic importance. Despite the front line's stabilization, Russia's main goal is still to capture the remaining cities in Donetsk Oblast. Russian forces have made inroads into the last remaining Ukrainian cities in the region, driving out what little civilian life is left.

Meanwhile, Ukraine's defending forces, reorganized under a new command structure, aim to grind down and stop any Russian offensive. The defense of Donetsk Oblast hinges on the "fortress belt," four industrial cities key to Ukraine's defense: Sloviansk, Kramatorsk, Druzhkivka, and Kostiantynivka. Since the invasion, these cities have been vulnerable to Russian drone strikes.

Since last year, the Ukrainian army's corps reform has positioned the defense of the fortress belt under two army corps: the 11th and 19th. Over May and June, Russian forces took control of Kostiantynivka, using a model of mass infiltration backed by drones, artillery, and glide bombs. Russian forces have attempted a double envelopment of the fortress belt, with two large pincers pushing north and south.

The northern pincer, bearing down on Lyman, saw Ukraine's Operation Vivaldi, a series of counterattacks by the country's 3rd Army Corps. Meanwhile, Russia concentrated immense pressure on the mining city of Dobropillia. With Russian forces learning to target Ukraine's weakened points, Kyiv has divided the defense of Donbas into two task forces led by high-profile commanders.