The corps, commanded by Andriy Biletsky, reported the gains in its Telegram channel, saying the operation's third phase proved decisive and returned 51 square kilometers of Ukrainian territory.
Biletsky named the village of Nove as the phase's main objective. "Whoever controls the heights around this settlement controls the initiative on the bridgehead," the statement said.
According to the corps, Russian troops expected the strike along the Shandryholove-Zelena Dolyna sector and moved reserves there. Biletsky claims the enemy expended those reserves in counterattacks on that axis, while the actual blow fell on Nove.
The corps put Russian losses at 2,000 personnel. It said more than 250 were taken prisoner, including officers, pilots and artillerymen. Biletsky said Russians "surrendered in whole units."
He said Soviet-era BTR-60 armored personnel carriers converted into robotic kamikaze systems were used to break through the defenses.
Russia's Defense Ministry has not commented on the Ukrainian claims. On the morning of September 28, it reported the capture of the settlement of Novovodyane in the Donetsk region.
The Ukrainian DeepState project, which maintains a battlefield map, confirmed the liberation of Redkodub, Nove and Katerynivka, as well as the restoration of control near Novomykhailivka and Lypove.
The Moscow Times, citing OSINT analyst Clement Molin, reported that Operation Vivaldi became Ukraine's largest offensive in the Donbas since 2022. According to Rochan Consulting's estimates, Ukrainian forces recaptured 240 square kilometers on this axis. By Molin's count, Vivaldi liberated twice as much territory as the 2023 counteroffensive.
Pro-war Russian Telegram channels have also reported problems in the Donetsk region. Two Majors called the situation on the sector difficult, and the Military Informant said the loss of positions complicates the advance on Sloviansk. Rybar linked the retreat to lies by army command, whose reports "do not square with reality."
The Institute for the Study of War (ISW) noted in publications overnight into September 28 a shift in Ukrainian tactics: instead of immediately eliminating penetrating forces, Ukrainian troops are focusing on disrupting Russian attempts to consolidate breakthroughs. ISW assessed that Ukraine's battlefield successes may be forcing Vladimir Putin to revise his "theory of victory" - from a calculation of collapsing the front around the Donbas fortress cities to a bet on long-range strikes in the winter of 2026-2027.