Ukraine's 3rd Army Corps reports completion of second stage of "Vivaldi" offensive in northern Donetsk Oblast

Why it matters

Operation "Vivaldi" is a confirmed, ongoing Ukrainian offensive on a section of the front where Russia had been trying to encircle the Sloviansk-Kramatorsk agglomeration and open a path toward Kharkiv, Dnipropetrovsk and Poltava oblasts. ISW assessed that the operation disrupted those Russian plans, and Ukrainian commanders said it has broken Russian intentions not only for 2026 but potentially into early 2027. The corps' claim of the first combat deployment of ground robotic kamikaze complexes delivered by heavy bomber drones points to a new technological dimension of the offensive.

What happened

Ukraine's 3rd Army Corps, commanded by Andriy Biletsky, publicly confirmed on 15 September that it is running a multi-stage offensive in northern Donetsk Oblast named "Vivaldi." On 19 September, the corps' chief of staff and deputy commander, Petro Horbatenko, reported that the first stage was still under way and that Ukrainian forces had additional advances, including the clearance of Rai-Oleksandrivka and other settlements whose names were withheld for tactical reasons.

On 20 September, Biletsky announced the completion of the second stage, during which Ukrainian forces liberated the villages of Shandryholove and Derylove in the Lyman community of Donetsk Oblast and established full control over Drobysheve. According to Biletsky, the second stage added 40 sq. km under Ukrainian control. Across both stages, the 3rd Army Corps and attached units reported 125 sq. km of territory returned, of which 50 sq. km were de-occupied.

Reported Russian losses during the first stage were around 1,500 soldiers, over 12,000 drones, and hundreds of units of armored vehicles, artillery systems and automotive equipment; the second stage added roughly 800 personnel, for a total of more than 3,000 across both stages. The 3rd Army Corps said the elite Russian UAV unit "Rubikon" was pulled from the Lyman-Borova direction because of heavy losses, and the DeepState monitoring project independently confirmed the liberations of Shandryholove and Derylove.

How Ukrainian sources describe it

All available sources are Ukrainian and frame "Vivaldi" as a successful, ongoing offensive that has foiled Russian encirclement plans, inflicted heavy losses on three Russian armies (the 20th, 25th and 1st Tank armies) and forced the elite Russian UAV unit "Rubikon" off the Lyman-Borova axis. Coverage centers on the 3rd Army Corps, with Biletsky and Horbatenko as the named authorities, and on DeepState as the independent confirmer of territorial gains. Ukrainian outlets emphasize both the strategic effect — disrupting Russian plans for 2026 and possibly early 2027 — and the technological novelty of the operation, including the claimed first-ever airdrop of NRK kamikaze ground robotic complexes by heavy bomber drones. Russian tactics are described in stark terms: "meat assaults," disorganized units being "ground into meat," and strikes on rear civilian areas including Izium, Balakliia, Sloviansk and Kramatorsk with aviation and Shahed drones.

Where reporting differs

Sources differ on the territorial scope of Ukrainian gains: French OSINT analyst Clément Molin claimed Ukrainian counteroffensive actions liberated more than 200 sq. km over four months, while the 3rd Army Corps officially reported 125 sq. km returned (50 sq. km de-occupied) across the first two stages. There is also variation in how Russian drone losses are presented: most sources cite "over 12,000" drones destroyed during the first stage, while some summarize the equipment losses more vaguely as "hundreds of pieces" without separating drones from other matériel, and a few entries present the 12,000 figure as an estimate rather than a confirmed total.

Background

Operation "Vivaldi" is a Ukrainian offensive in northern Donetsk Oblast run by the 3rd Army Corps under commander Andriy Biletsky, with chief of staff and deputy commander Petro Horbatenko as the corps' public spokesperson. Biletsky first confirmed the operation publicly on 15 September; Horbatenko provided further updates on 19 September; the second stage was announced on 20 September. According to Horbatenko, eliminating a Russian bridgehead on the western bank of the Chornyi Zherebets River derailed a Russian plan to encircle the Sloviansk-Kramatorsk agglomeration from the south via Izium and to use that as a springboard for further advances into Kharkiv, Dnipropetrovsk and Poltava oblasts. Russian forces continue offensive attempts toward Sloviansk and Kramatorsk and are striking rear areas including Izium, Balakliia, Sloviansk and Kramatorsk with aviation and Shahed drones. On 18 September the 3rd Army Corps reported that the elite Russian UAV unit "Rubikon" had been pulled off the Lyman-Borova direction because of heavy losses during "Vivaldi."