Ukrainian troops pushed into a front-line village Russian forces were sure they could never reach, an officer from the assault force told Army TV. He described a methodical, house-by-house clearing—then a Russian response that, once the village fell, called the footage an AI fake.

Through 2026 Russia has pressed on this stretch of the eastern front, creeping toward the fortress belt, the chain of fortified cities anchoring Donetsk Oblast. Retaking Serednie is one move in a quiet Ukrainian counteroffensive that has clawed back ground on this axis—which is why this village changing hands lands harder than the map suggests.

The terrain Russia trusted

Serednie sits on the Lyman direction in eastern Ukraine, an axis where Russian forces have been pressing toward Ukrainian-held Sloviansk and Kramatorsk. Troops from Ukraine's 66th Separate Mechanized Brigade entered the village during Operation Vivaldi, said the deputy commander of its first mechanized battalion, Kassta, callsign Timokha.

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Sitting on their own gains there, the Russians assumed no counterattack could follow and were certain the terrain itself ruled out any move into the village.

"The enemy, having success in this direction, did not expect that any counterattack or offensive could come in response," Timokha said.

Preparing for the operation took more than a day or two, he added, because the village was full of basements and buildings that each had to be checked. Reconnaissance came first, then fire from drones, heavy bomber drones, and artillery to grind down a garrison he put at at least a platoon, before assault groups moved in with friendly units alongside.

Operation Vivaldi as a whole, run under an information blackout, has cleared 75 km² of enemy infiltration pockets and de-occupied another 10.

Then the Russians called it AI

Small Russian attempts to retake the village broke apart on the approaches, Timokha said. The louder reaction came online: Russians claimed the Ukrainian liberation videos were made with artificial intelligence.

He likened it to Sviatohirsk, where Vladimir Putin announced the town's capture before the commander of Ukraine's Third Army Corps, Brigadier General Andrii Biletskyi, publicly denied it, Timokha said.

Ukraine’s Third Army Corps has revealed details of an offensive operation in northern Donetsk Oblast, saying its forces cleared Russian infiltrators from several settlements and liberated the village of Serednie.

Russia has made seizing the entirety of Donetsk Oblast both a battlefield and diplomatic priority of its invasion of Ukraine, repeatedly trying to break through heavily fortified Ukrainian defensive lines while demanding that Kyiv withdraw from the remaining Ukrainian-held territory in negotiations. Despite years of fighting and sustained Russian assaults, Moscow has failed to capture the entire oblast, and Ukraine is now conducting an offensive of its own.

The operation, dubbed “Vivaldi,” was conducted under a period of information silence and involved Ukrainian drone, reconnaissance, special operations, infantry, and other units working under a unified tactical command. The corps said the first phase cleared 75 square kilometers of Russian infiltrators and liberated another 10 square kilometers of territory.

The announcement was made by Third Army Corps commander Brigadier General Andrii Biletskyi on 15 September. 

Ukraine targets Russian infiltration

According to the corps, the operation focused initially on Russian troops that had infiltrated Ukrainian positions and settlements in the area.

Ukrainian forces cleared Novoselivka, Oleksandrivka, Yarova, the outskirts of Korovyi Yar, and liberated Serednie, the corps said. It described the total area cleared or retaken as 85 square kilometers.

The operation brought together units from the 60th and 125th Mechanized Brigades, the Third Assault Brigade, the KRAKEN special unit, and other formations of the Third Army Corps, alongside attached units from the 66th Mechanized Brigade, Ukraine’s Special Operations Forces, the military intelligence unit Artan, and the State Border Guard Service.

The corps said the operation was coordinated by a joint headquarters that brought special operations and reconnaissance units under a single tactical plan specifically to counter Russian infiltrators, whom it referred to as “flagovtyky.”

Russian logistics pushed back across the border

The Ukrainian operation also targeted Russian logistics supporting the front.

The corps said its drone units cut Russian supply routes and struck fuel infrastructure and storage facilities that had been supporting Russian forces.

According to the Ukrainian military, Russian forces subsequently moved the supply of fuel and lubricants out of Ukraine and into Russia’s Voronezh Oblast after a pipeline and fuel depots were destroyed.

The corps claimed Russian forces lost around 1,500 personnel during this phase of the operation, as well as more than 12,000 drones and hundreds of armored vehicles, artillery systems, and other vehicles.

‘This is only the first season’

Biletskyi said the operation’s ultimate objective has been the subject of speculation in open sources, with some reports suggesting Ukrainian forces could be seeking to reach the Chornyi Zherebets River.

He declined to confirm that objective, instead emphasizing the name of the operation.

“Our operation is called Vivaldi. And Vivaldi, as is known, has four seasons. And this is only the first one,” Biletskyi said.

The remarks suggest Ukraine does not consider the actions revealed on 15 September to be a standalone tactical operation, although the corps did not disclose what its next phase will involve.

The Third Army Corps said further details would be released in subsequent official statements.

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Donetsk remains Russia’s main territorial objective

Donetsk Oblast is central to Russia’s territorial demands in Ukraine. Moscow claims the entire oblast as Russian territory despite not controlling all of it, and has demanded that Ukraine withdraw from the remaining Ukrainian-held territory in Donetsk as part of peace talks.

The Donbas region – consisting of Donetsk and neighboring Luhansk oblasts – has been a battleground since Russia’s 2014 invasion, and capturing the remaining Ukrainian-held territory has remained the Kremlin’s core objective throughout the full-scale invasion since 2022.