Ukrainian forces are advancing east of Sloviansk and Kramatorsk, and even Russian milbloggers now acknowledge it, the Institute for the Study of War (ISW) said on 8 October. The gains may follow months of groundwork like the one that preceded Operation Vivaldi near Lyman, which Ukraine says returned 176 km² to its control. Russian commentators are already doubting that Moscow can reach the two cities.

Russia's years-long push on the Fortress Belt, the chain of cities anchoring Ukraine's defense in Donetsk Oblast, has been stalling since Vivaldi began. Unable to take those cities, Russia keeps hitting them from the air. On 8 October, a Russian bomb killed 30 people on two buses in Kramatorsk.

Across the Siverskyi Donets

Russian milbloggers said Ukrainian forces liberated Ozerne and advanced east of Pyskunivka toward Kryva Luka, ISW reported. They also acknowledged that Ukrainian troops drove Russian forces out of Pyskunivka. Ukrainians are now counterattacking toward Kryva Luka from the west and northwest, from across the river.

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Vivaldi counteroffensive advanced after Ukraine took Russia’s drones out of the fight, ISW assesses

ISW called the repeated Russian claims of a river crossing notable, because the Siverskyi Donets is a significant natural obstacle. Kryva Luka is a dominant height just south of the river. From there, Ukraine could launch further counterattacks. Ukrainian forces appear to have pushed Russian troops off both banks in this area, ISW assessed.

The heights Russia wanted

After Vivaldi cleared ground near Lyman in September, Russia shifted its push south toward Mykolaivka and Sloviansk. Russian forces likely see Mykolaivka, just east of Sloviansk, as a primary objective, ISW said. Its heights would favor an offensive on the city. Ukrainian pushes northeast and southeast of the town now deny Russia that terrain.

East of Kramatorsk, milbloggers claimed Ukrainians liberated Malynivka and advanced between Fedorivka Druha and Holubivka. They also reported gains into southern Minkivka and near Fedorivka. The lines remain tangled. Geolocated footage shows Ukrainian forces striking a Russian position in central Tykhonivka after what ISW assesses was a Russian infiltration.

ISW said the counterattacks may point to a broader Ukrainian goal: pushing Russian forces east, away from the Sloviansk–Kramatorsk area and toward the Siverskyi Donets–Donbas Canal.

The Vivaldi playbook

The counterattacks have run for weeks. On 29 September, Ukrainian military observer Kostiantyn Mashovets reported them in the same areas, saying Russia's 3rd Combined Arms Army had failed to make significant gains. ISW assesses that the attacks build on months of shaping meant to wear down Russia's offensive capacity.

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Vivaldi’s secret weapon was the targeting, not the robots: Third Corps reconnaissance mapped Russian command nodes, then hit them to cause panic

Before Vivaldi, Ukrainian forces targeted Russian drone operators, gaining drone superiority before the counteroffensive. They used the same approach ahead of their Oleksandrivka counterattacks in early 2026.

Moscow appears to see the pattern. A Ukrainian military official said on 7 October that Russia is moving drone units and Spetsnaz from quieter sectors to the Sloviansk–Kramatorsk direction. Ukraine also reorganized its command in and around Donetsk Oblast in early September, which may be blunting Russian attacks from the east, ISW said.

"Distant" and "doomed"

One Russian milblogger called an advance toward the Sloviansk–Kramatorsk area a "distant" prospect, ISW reported. A Russian offensive from Siversk toward Sloviansk may be "doomed" to failure or heavy losses unless Russia retakes the forests south of Lyman, he said.

The counterattacks east of the two cities appear to support Vivaldi, ISW assessed. Together with Russia's defeat north of the river, they could disrupt Russia's offensive toward Sloviansk from the east entirely.

If Ukraine holds Kryva Luka and keeps Russia off the Mykolaivka heights, Moscow's pincer on Sloviansk and Kramatorsk loses the ground it was built on.

Ukraine's Vivaldi counteroffensive rolled back a Russian advance north of Lyman in Donetsk Oblast. However, Moscow shifted part of its forces south, Roman Pohorilyi, co-founder of the Ukrainian battlefield mapping project DeepState, told Radio NV. Russian troops are now infiltrating Mykolaivka, a key strongpoint on the approach to the fortress city of Sloviansk, Pohorilyi said.

The halted advance was one arm of Russia's plan to encircle Ukraine's Donetsk fortress belt—the fortified cities of Sloviansk, Kramatorsk, Druzhkivka, and Kostiantynivka. Pohorilyi warned that losing Mykolaivka would create serious problems for Sloviansk's defenders. Russia is still pressing toward Dobropillia on the belt's southwestern flank.

Pohorilyi said Russia formed a "claw" north of Lyman by exploiting Ukrainian brigades short of personnel and pushing small groups into their lines. Ukraine's Third Army Corps stabilized the area, built up forces, and counterattacked. The push "multiplied all [Russia's] previous efforts by zero," he said.

Russian forces had repeatedly tried to capture or bypass Lyman, Pohorilyi said. Russian groups still infiltrate the approaches to the city, although Ukrainian forces have stabilized the situation there.

The corps says Vivaldi's first two phases regained control of 125 square kilometers, including 50 that had been under Russian occupation. It reported liberating Shandryholove and Derylove, securing Drobysheve, and inflicting more than 3,000 Russian personnel losses. Those battlefield figures have not been independently verified.

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Vivaldi’s secret weapon was the targeting, not the robots: Third Corps reconnaissance mapped Russian command nodes, then hit them to cause panic

Pohorilyi noted that the area around Mykolaivka had, until recently, been under the responsibility of Ukraine's 11th Army Corps and is now under the Third Army Corps.

Ukrainian troops must now find and stop infiltrating Russian groups before they establish control, he said. Personnel shortages on the Lyman axis persist, although he said reinforcements are being distributed more evenly.

Operation Vivaldi and the wider fight for Donetsk's fortress belt

The Third Army Corps first disclosed Operation Vivaldi on 15 September after conducting the counteroffensive north of Lyman under information silence. Commander Andrii Biletskyi said the announced gains were only the first phase; the corps said its attacks had disrupted Russian supply routes.

A 60th Mechanized Brigade captain said Ukrainian units quietly assembled near Derylove and Drobysheve, then struck Russian drone launch sites at planned times so infantry could advance. The corps disclosed a second phase on 20 September.

Farther southwest, Dobropillia faces even heavier pressure, Pohorilyi said. Russia has concentrated large forces there and is pushing with relentless infantry across a wide front, backed by thousands of drones each month—reconnaissance, strike, FPV, and Lancets—with numbers still rising. Russian troops are moving on settlements south of Dobropillia to establish a strongpoint and push deeper into Donetsk Oblast.

The pressure is not new: Biletskyi said Ukrainian troops halted a Russian incursion there last year. After Moscow claimed on 22 September to have encircled the town, the Institute for the Study of War found no evidence to support the claim.