Ukraine blocks Russia from outflanking its fortress cities in Donbas, retaking 277 square kilometers and hitting 8,000 Russian troops

Ukraine successfully completed Operation Vivaldi, a military campaign aimed at protecting its fortified cities in the Donetsk Oblast region of eastern Ukraine. The operation, which consisted of four phases, resulted in Ukraine regaining control over 277 square kilometers of territory and inflicting significant casualties on Russian forces.

Brigadier General Andrii Biletskyi, the commander of the Third Army Corps leading the operation, reported that the fourth phase secured an additional 101 square kilometers of territory. This included the liberation of three settlements—Zelena Dolyna, Lypove, and Kolodiazi.

The main objective of Operation Vivaldi was to improve defensive positions for Ukrainian troops by moving them into more advantageous locations. The operation thwarted Russian efforts to outflank the Sloviansk-Kramatorsk agglomeration and cut the Kharkiv–Sloviansk highway, a crucial supply route for Ukrainian forces in the Donbas region. By preventing these actions, Ukraine was able to alleviate pressure on Kupiansk-Vuzlovyi.

During Operation Vivaldi, Ukraine worked against Russia's deadline for seizing Donetsk Oblast. Russian President Vladimir Putin had previously stated his confidence that Russian forces would be able to take the entire region by the end of 2026. Ukraine's military mission was to prevent this from happening.

The operation began on September 15, 2026, with the first phase involving the clearing of Russian groups from 75 square kilometers of territory and the liberation of an additional 10 square kilometers. This phase saw Ukrainian troops strike Russian supply routes and fuel infrastructure, which led Russia to relocate its fuel and lubricant reserves to Voronezh Oblast. The Russian forces reportedly lost around 1,500 troops, over 12,000 drones, and numerous pieces of equipment during this phase.

The second phase of Operation Vivaldi took place on September 20, during which Ukrainian forces liberated Shandryholove and Derylove and established full control over Drobysheve. Russian forces lost another 800 troops during this phase, bringing their total losses across the first two seasons to more than 3,000. The third phase, reported on September 28, saw the liberation of Nove, Ridkodub, and Katerynivka, along with the restoration of control over Karpivka and Novomykhailivka, adding another 51 square kilometers to Ukraine's liberated territory.

Russian forces suffered around 2,000 casualties and had over 250 taken prisoner in this phase as well.

In summary, Operation Vivaldi was a successful campaign by Ukraine to protect its fortified cities in the Donetsk Oblast region and prevent Russia from outflanking these key areas. The operation resulted in Ukraine regaining control over 277 square kilometers of territory and inflicting significant casualties on Russian forces, thereby thwarting Russian plans to seize the entire Donetsk Oblast.