Russia’s Rubicon drone unit, which is sent to hunt Ukrainian drone pilots, was not used to being hunted itself, Brigadier General Andrii Biletskyi told journalists on 19 October. He was summing up Operation Vivaldi, which his Third Army Corps fought in northern Donetsk Oblast from May to mid-October. Once its pilots realized they were being killed, Rubicon’s morale dropped sharply, he said.

Russia has fought for 12 years to take all of Donetsk Oblast, and Sloviansk and Kramatorsk anchor the fortress belt of cities Ukraine still holds there. Vivaldi retook 277 km² in northern Donetsk Oblast. Biletskyi says it destroyed Russia’s bridgehead on the Chornyi Zherebets River and forced Moscow to drop its plan to bypass Lyman from the north and encircle the two cities. On that front, the Third Corps had flagged Rubicon, Russia’s elite drone unit, as a threat.

Hunting the hunters

Once a Rubicon position was found, the Third Assault Brigade and the KRAKEN drone regiment committed any number of FPV and bomber drones to destroy its crews, Biletskyi said.

The brigade’s commander, Yaroslav Levenets, said his troops prepared for Rubicon’s arrival and concentrated on killing its pilots. He gave no details.

“Not stable in defense,” Levenets said of Rubicon’s troops.

They dislike sitting in trenches, he said, and under pressure they grow nervous and change positions.

Named for four seasons

Biletskyi said the name was chosen at the very start of planning, in winter 2025–2026, many months before the operation began. The original plan had four stages, one for each season, and later grew to slightly more, ArmyInform reported.

When he first unveiled the operation in September, he put it this way:

“Vivaldi, as is known, has four seasons. And this is only the first one.”

He credited two planners, known by the call signs Yurist and Leshyi. Leshyi, an assault soldier wounded seven times who later moved to staff work, was killed. Yurist was seriously wounded.

A new hand at the Third Corps

Major Dmytro Rohoziuk is now acting commander of the Third Army Corps, the corps press service said on 20 October. The press service said the move is not a transfer, and Biletskyi keeps his formal post as corps commander while he leads the “Center” grouping of the Third, 11th, and 19th corps.

Rohoziuk took over the 60th Mechanized Brigade in October 2025. Its previous commander was arrested in January after the State Bureau of Investigation accused him of embezzling about $1 million in weapons procurement. The brigade fought in all four phases of Vivaldi and retook Kolodiazi without street fighting.

Biletskyi also declined command of the Ground Forces, which oversee mobilization.

“There’s no point taking on something you don’t truly believe you can improve,” he said.

Biletskyi’s count

Russian losses in Vivaldi topped 8,000 troops, and about 270 Russian soldiers were taken prisoner, Biletskyi said. More than 20 officers surrendered, including a chief of staff and three company commanders.

The territory matters less than disrupting Russia’s strategic plan, he said. Russian forces still press toward Dobropillia, where Ukraine is counterattacking.

Ukrainian infantry encircled and retook the village of Kolodiazi north of Lyman without getting drawn into street fighting, while a drone battalion kept the sky above them shut, the battalion’s chief of staff told Suspilne on 18 October. The village fell during the fourth and final phase of Operation Vivaldi, Ukraine’s counteroffensive in northern Donetsk Oblast.

For years now, Russia has aimed to seize Lyman and cross the Siverskyi Donets River. It needs this area to encircle Ukraine’s fortress belt of Donetsk Oblast cities from the northwest, ISW assesses. Vivaldi’s four phases retook 277 km² and 16 settlements on that approach, and a veteran of the operation has said Ukraine’s assault troops suffered more than ten times fewer casualties than Russian forces doing it.

Drones over the infantry

The 60th Mechanized Brigade fought in all four phases of Vivaldi and took Kolodiazi in the last one, said the chief of staff of the brigade’s Fatum unmanned systems battalion, callsign Krash.

“Our task, as an unmanned systems battalion, was to escort and ‘close’ the air in front of our infantry to make it impossible for the enemy to hit it. To suppress all the firing assets possible,” he said.

The brigade’s 3rd Mechanized Battalion, the main striking force, encircled Kolodiazi and retook it without getting drawn into street fighting, Krash said. The 1st Mechanized Battalion kept Russian reinforcements out of the area, while drone crews suppressed artillery, hit supply runs, and worked against Russian drone operators.

500 troops and 200-plus vehicles

The drone battalion killed or wounded about 500 Russian troops during the fourth phase and struck Russian armored vehicles, trucks, and motorbikes, its chief of staff said.

“More than two hundred pieces of various equipment: Grad and Uragan multiple rocket launchers, various armored vehicles, tanks, armored combat vehicles. Most of all motorbikes and quad bikes, there the count runs into the hundreds. This is our enemy’s main logistics tool,” he said.

Ghost villages

The villages retaken in northern Donetsk Oblast are nearly empty of civilians, Krash said.

“It’s very typical for de-occupied settlements: these are ghost towns. You can see right away where the occupier stepped. All the settlements are under the control of the Third Army Corps, our forces stand there and prevent enemy infiltration. But civilian life in these towns is either absent or very scarce,” he said.

Third Army Corps commander Brigadier General Andrii Biletskyi reported Kolodiazi’s liberation, along with Zelena Dolyna and Lypove, when he summed up Vivaldi’s fourth phase, which secured 101 km².