Ukraine’s Operation Vivaldi foils Russia’s plan to encircle the Donbas, ISW analysis shows

What was Operation Vivaldi, and how did it disrupt Russia’s planned advance in the Donbas?

Operation Vivaldi was Ukraine’s counter-offensive along the Lyman axis. Its purpose was to break the northern arm of Russia’s planned encirclement of the Ukrainian-held Donetsk region. This mattered because Russia’s wider campaign depended on linking advances from the north and south-west near Barvinkove.

Ukrainian forces advanced along two lines: Ridkodub–Nove–Novomykhailivka in the north, and Yarova–Drobysheve–Stavky in the south. These movements collapsed the salient Russia had built to threaten Sloviansk from the north-east. The operation also removed Russian positions intended to threaten the fortress belt’s northern approaches.

The result was an operational failure for Russia. It abandoned plans to advance on Sloviansk from the north-east and lost control of important ground around Lyman. Russia’s remaining advance from Pokrovsk–Dobropillia now faces more ambitious objectives without the northern arm supporting it.

What is a pincer movement, and how was Russia trying to use one to encircle Ukrainian-held Donetsk?

A pincer movement is an attack from two directions designed to close around an opposing force or territory. The two advancing arms try to meet behind the target, cutting routes and creating an encirclement. This can isolate defenders and make their positions much harder to supply or reinforce.

Russia planned a deep pincer against the Ukrainian-held portion of Donetsk. One arm advanced from Lyman in the north. The other moved from the Pokrovsk–Dobropillia area in the south-west. The plan called for both arms to link near Barvinkove in the Kharkiv region, surrounding the fortress belt.

Ukraine’s counter-offensive broke the northern arm before that link-up could happen. Russia still retained limited gains near Kostyantynivka and east of Sloviansk, but the original encirclement plan lost a crucial component. The surviving southern arm now carries far more ambitious objectives alone.

How much territory did Ukrainian forces reportedly retake around the Lyman axis, and why do the Ukrainian and ISW figures differ?

The reported Ukrainian gains around the Lyman axis range from 125 to 176 square kilometres. Commander Andrii Biletskyi said the first three phases of Operation Vivaldi liberated 176 square kilometres in mid- to late September. President Volodymyr Zelenskyy gave a figure of 125 to 140 square kilometres as of 3 October.

The article does not identify one definitive reason for the difference. It presents figures from different Ukrainian officials, covering different dates and possibly different ways of measuring territory. ISW made its own assessment using open-source intelligence, including geolocated footage, satellite imagery and visually confirmed data.

ISW suggested the operation may have been more successful than Kyiv’s official figures reflected. The key point is not only the precise area, but the strategic result: Ukraine dismantled Russia’s northern pincer and preserved control of the Lyman area and its supply routes.

Why is the fortress belt important to Ukraine’s defense of the remaining Ukrainian-held part of Donbas?

The fortress belt is a defensive and logistical network protecting the Ukrainian-held portion of the Donbas. It matters because it links defensive positions with the routes needed to move troops, equipment and supplies. Holding that network helps Ukraine keep its remaining territory connected and resist advances.

Russia’s planned pincer was aimed at surrounding this belt. Its northern arm advanced from Lyman, while its southern arm moved from the Pokrovsk–Dobropillia area. The arms were intended to meet near Barvinkove. A completed encirclement would have threatened the belt from multiple directions and supported Moscow’s objective of occupying all Donetsk.

Ukraine’s success around Lyman preserved the belt’s northern approaches and key supply routes. It also forced Russia to abandon its planned north-eastern advance on Sloviansk. Russia’s surviving southern arm must now pursue the campaign without the northern pressure that was meant to help close the encirclement.

What changed for Russia’s campaign after the northern arm of its pincer collapsed?

The collapse of the northern pincer changed Russia’s campaign from a coordinated encirclement attempt into a less complete advance. Russia had planned to pressure the fortress belt from north and south, then link the two arms near Barvinkove. That design no longer worked after Ukraine’s counter-offensive around Lyman.

Russian forces had to abandon plans to advance on Sloviansk from the north-east. They also lost positions intended to threaten the northern approaches to the fortress belt. Ukraine retained control of the Lyman area and preserved important supply routes. Russian units elsewhere may have been redeployed to reinforce the northern sector.

The surviving advance from Pokrovsk–Dobropillia now faces more ambitious objectives on its own. ISW called the northern pincer’s collapse an operational failure. Russia retains limited gains near Kostyantynivka and east of Sloviansk, but its advance has struggled to maintain momentum.

Why do supply routes and control of the Lyman area matter so much to the movement and survival of armies?

Supply routes matter because armies need continuous movement of ammunition, food, fuel, equipment and replacements. They also provide routes for shifting units toward threatened sectors or away from danger. If an army loses those links, frontline positions can become isolated and harder to sustain.

The article says Ukraine’s control of the Lyman area preserved key supply routes. That helped protect the fortress belt and prevented Russia from using its northern positions to threaten the belt’s approaches. The defeat also meant Russian units elsewhere may have had to redeploy toward the northern sector, rather than maintaining pressure across the front.

This makes Lyman important beyond the territory immediately retaken. Control of the area affected the movement and survival of forces across the wider campaign. Russia’s plan depended on building pressure from two directions, but Ukraine’s retention of Lyman kept the northern side connected to Ukrainian defenses and supply networks.

Why are fast mechanized maneuvers often more capable of breaking defensive lines than gradual infantry infiltration, drones, and bombardment alone?

Fast mechanized maneuvers can break defensive lines by combining speed, protection and concentrated force. They can exploit a weak point, push through it quickly and threaten positions behind the front. That can disrupt the defender’s organization before reinforcements arrive or a new line is formed.

The article contrasts this with Russia’s reliance on infantry infiltration, drones and bombardment. Those methods can produce gradual attrition, meaning they slowly wear down personnel and positions. But ISW said they cannot create the fast mechanised manoeuvres needed to collapse Ukraine’s defenses at the scale Moscow requires.

This helps explain why Russia has struggled to sustain its advance around Kostyantynivka and east of Sloviansk. Gradual pressure may gain ground, but it has not produced the rapid operational collapse Russia’s encirclement plan required. ISW said Russia may adapt through mobilisation and technology, though neither would necessarily create a breakthrough.

Key Facts:

📌 Operation Vivaldi was Ukraine’s counter-offensive on the Lyman axis.

📌 It collapsed Russia’s northern pincer arm threatening Sloviansk.

📌 The operation forced Russian units onto the defensive.

📌 A pincer attacks from two directions to close around a target.

📌 Russia planned advances from Lyman and Dobropillia.

📌 The two arms were intended to link near Barvinkove.

📌 Biletskyi reported 176 square kilometres liberated.