Ukraine’s Operation Vivaldi Disrupts Russia’s Plan to Encircle the Donbas

Ukraine’s counteroffensive near Lyman has undermined a key component of Russia’s campaign to capture the remaining Ukrainian-held parts of Donetsk region, forcing Moscow to reconsider the operational logic of its advance.

Ukraine’s Operation Vivaldi has disrupted Russia’s attempt to encircle the Ukrainian-held part of Donetsk region from the north and south, according to an assessment by the Institute for the Study of War (ISW). The counteroffensive around Lyman has dismantled the northern flank of the planned Russian pincer movement, weakening Moscow’s ability to threaten the Ukrainian defensive network around Sloviansk and Kramatorsk.

The operation represents a significant setback for Russia’s campaign to seize the remaining Ukrainian-controlled territory in Donetsk region. Rather than simply reclaiming ground, Ukrainian forces have undermined the wider offensive plan by removing positions that were intended to support an advance towards the region’s principal defensive belt. The result is a more difficult operational situation for Russian troops attempting to advance from the southwest.

The Russian plan to surround Donetsk’s defensive belt

Russia’s campaign was designed around a coordinated advance from two directions. Forces operating near Lyman in the north were expected to push towards Sloviansk, while troops advancing from the Pokrovsk–Dobropillia area in the southwest were intended to create the other arm of the encirclement. The two forces were supposed to converge near Barvinkove in Kharkiv region, cutting off Ukrainian positions and threatening the wider defensive network.

This so-called fortress belt is not a single line of fortifications. It comprises a network of defended cities, settlements, transport routes and logistical infrastructure that has helped Ukraine resist Russian advances in Donetsk region. Sloviansk and Kramatorsk are central to this system, making the approaches to them strategically important for both sides.

For Moscow, encircling the area would have offered a potential route towards capturing the remaining Ukrainian-held parts of Donetsk region while putting Ukrainian units under pressure to withdraw or risk being surrounded. It would also have provided the Kremlin with a major territorial objective to present as an achievement after years of costly warfare.

Operation Vivaldi has undermined that approach. Ukrainian forces advanced across several areas around Lyman, pushing Russian troops out of positions that threatened the defensive belt from the northeast. According to ISW, the northern component of the planned pincer has effectively collapsed, making the original encirclement plan substantially more difficult to execute.

Counteroffensive gains change the battlefield equation

Ukraine’s operation targeted Russian positions along several axes around Lyman, including the areas of Ridkodub, Nove and Novomykhailivka to the north, as well as Yarova, Drobysheve and Stavky to the south. These advances weakened the Russian salient — a projection of troops and positions into Ukrainian-held territory — that had threatened Sloviansk from the northeast.

The reported territorial gains vary according to the source and the stage of the operation. Andrii Biletskyi, commander of Ukraine’s 3rd Army Corps, said the first three phases had liberated 176 square kilometres. President Volodymyr Zelenskyy cited a more conservative figure of between 125 and 140 square kilometres as of 3 October. ISW assessed that the overall gains may have exceeded the publicly reported figures.

The operational consequences extend beyond the territory recovered. By removing Russian positions around Lyman, Ukrainian forces have reduced the threat to supply routes and strengthened their ability to defend the northern approaches to the fortress belt. Russian troops can no longer rely on the same positions to support a coordinated advance towards Sloviansk.

The counteroffensive has also forced Russian units in the area to respond to Ukrainian pressure rather than concentrate exclusively on their own offensive objectives. That shift can consume personnel and resources that Moscow would otherwise use to sustain attacks elsewhere along the front.

Russia’s remaining offensive faces greater difficulties

The failure of the northern flank does not mean Russia has abandoned its campaign to capture Donetsk region. Russian forces continue to attack along several axes, including around Pokrovsk, Dobropillia and Kostyantynivka, while seeking to advance towards Sloviansk from the east.

However, the southern and southwestern components of the original plan now face a more difficult task. Without the northern advance, Russia would have to achieve substantially more from its remaining directions to recreate the threat of a broad encirclement. Its forces would also have to contend with Ukrainian positions that can continue disrupting their movements and supply lines.

ISW has highlighted the limitations of Russia’s reliance on infantry infiltration, drone operations and bombardment. These methods can gradually wear down Ukrainian defences and create local pressure, but they do not necessarily deliver the rapid, coordinated manoeuvres required to encircle a large defensive network. Russia may continue making local gains without achieving the operational breakthrough needed to change the wider situation.

The distinction is important. Capturing individual settlements or establishing a presence in contested areas does not automatically translate into control of territory, a secure supply corridor or the ability to sustain a larger offensive. The fighting around Donetsk demonstrates how local advances can fail to deliver the strategic result Moscow is seeking.

Battlefield claims and the limits of Russian progress

The assessment of Operation Vivaldi also raises questions about Russian claims of territorial gains. Moscow has continued presenting its offensive as a campaign of steady advances, while Ukrainian counterattacks and independently verified battlefield evidence have complicated that narrative.

In its analysis, ISW challenged Russian claims that Moscow’s forces had captured an additional 1,301 square kilometres of Ukrainian territory in September. Using geolocated footage, satellite imagery and other visually confirmed information, the institute assessed that Russian forces had lost territory on balance during the month, including ground recovered by Ukraine around Lyman.

ISW estimated that Russian forces lost a net 175.18 square kilometres in September when areas that Russian troops had entered but failed to hold were included in the calculation. This differs substantially from the picture presented by Russian officials. The institute also disputed President Vladimir Putin’s claim that Russia controlled 89% of Donetsk region, estimating the share at no more than 81%.

Such figures remain assessments based on available evidence rather than a complete record of every position on the battlefield. Frontline control can change quickly, and visual confirmation may lag behind developments. Nevertheless, the discrepancy illustrates why territorial claims should be evaluated against independently verifiable evidence rather than official announcements alone.

Inflated reports of progress can also distort military planning. If commanders base operational decisions on exaggerated accounts of territorial gains, they risk underestimating Ukrainian resistance, overlooking exposed positions and committing additional forces to objectives that are harder to achieve than reported.

A setback, not the end of Russia’s campaign

Operation Vivaldi has disrupted Russia’s plan to encircle the Donbas fortress belt, but the longer-term consequences will depend on whether Ukraine can maintain its gains and whether Russian forces can adapt. ISW has cautioned that the battlefield remains fluid and that Moscow may change its approach over time. Additional mobilisation, tactical adjustments and renewed pressure on other parts of the front could alter the situation.

For Ukraine, holding the gains around Lyman will be essential. The operation’s value lies not only in the territory recovered but also in preserving routes, protecting the northern approaches to Sloviansk and making it harder for Russian forces to coordinate advances from opposite directions. Continued pressure on Russian logistics could further limit Moscow’s ability to rebuild the offensive.

The operation also illustrates the importance of timing, operational security and concentrating force against vulnerable parts of an opponent’s deployment. Ukraine’s counteroffensive has disrupted a broader Russian plan rather than merely responding to individual assaults. That makes it a meaningful operational achievement, even if it does not by itself remove the threat to the rest of Donetsk region.