Ukraine's Lyman push collapses Kremlin plan to encircle Donbas fortress cities — ISW

Ukraine’s defense forces secured an operationally vital objective by breaking Russian attempts to envelop Ukraine’s key "fortress belt" as a result of operation. Tactical and operational gains achieved north of Lyman have rendered Moscow’s already unrealistic campaign design to encircle the fortress cities from both north and south entirely unviable, the Institute for the Study of War (ISW) concluded in its assessment.

A prominent Kremlin-affiliated Russian military blogger endorsed the ISW assessment, conceding that Ukrainian counteroffensive momentum will substantially delay Moscow’s projected drive against Slovyansk — a primary operational objective intended to follow the conquest of Lyman. The blogger acknowledged that the northern flank of the Russian Southern Group of Forces (deployed southeast of Lyman and east of Kramatorsk) has been rendered acutely vulnerable to Ukrainian counterattacks and logistics interdiction missions.

According to Russian milbloggers, Russian forces have also yielded ground south of Lyman, leaving them unable to restore tactical footholds inside the city due to continuous Ukrainian advances. Commentators directly blamed field commanders and the military's pervasive culture of "fabricated progress reports," noting that systematically inflated territorial claims forwarded to higher headquarters corrupt theater-level operational planning.

Another prominent military observer disclosed that several Russian commanders attempted to conceal massive casualty rates by hastily forming emergency assault detachments from untrained replacement personnel in desperate bids to recapture lost ground, even as senior military leaders in Moscow remain privately aware of operational realities on the ground.

ISW analysts observed that Russian forces persistently prioritize frontal assaults aimed at pushing toward the fortress belt from the south and enveloping it from the southwest, rather than attempting direct pushes from the east — despite the tactical collapse of their Lyman push. Military analysts assessed that Russian senior command either failed to grasp the permanent loss of the Lyman salient and tactical initiative in the sector, or was stubbornly trying to sever Ukrainian ground lines of communication leading into the fortress belt from the west.

The Institute emphasized that Russian operational headquarters is prioritizing domestic information effects, striving to fabricate an illusion of continuous advances in Donetsk Oblast so the Kremlin can market battlefield momentum domestically and abroad. However, Ukraine’s counteroffensive maneuvers continue to undermine these efforts, with Ukrainian formations expected to declassify further battlefield gains as Operation Vivaldi progresses.

Operation Vivaldi: 3rd Army Corps declassification

Liberated territory: On Sept. 15, Ukraine’s 3rd Army Corps formally confirmed the counteroffensive across northern Donetsk Oblast, clearing Russian forces from Novoselivka, Oleksandrivka, Yarova, and the outskirts of Koroviy Yar, while fully liberating Serednye in the Lyman municipality.

First of four phases: Releasing combat footage of liberated terrain, 3rd Army Corps Commander Andrii Biletskyi confirmed the maneuvers under the title Operation Vivaldi, noting the breakthrough toward the Chornyi Zherebets River marks only the opening phase of a multi-season campaign.

Russian attrition: Russian forces sustained an estimated 1,500 personnel casualties, the loss of over 12,000 reconnaissance and strike drones, and hundreds of destroyed armored fighting vehicles, artillery pieces, and logistics vehicles during this operational phase.

Logistics severed: Ukrainian strike drone teams systematically cut Russian ground supply routes, forcing Russian military logistics to withdraw forward fuel and lubricants depots out of Ukrainian territory entirely and relocate them to Voronezh Oblast.