September 15 – October 14, 2026 · Northern Donetsk Oblast — Lyman sector Theater
September 15 – October 14, 2026
Ukraine's 3rd Army Corps, commanded by Andriy Biletsky, publicly announced Operation Vivaldi on September 15, 2026, after weeks of strict information silence. Its aim was to stop a Russian approach to Sloviansk and Kramatorsk from the north, through the Lyman sector. In four phases the corps cleared infiltration pockets and retook villages including Serednie, Shandryholove, Derylove, Drobysheve, Karpivka, Ridkodub, Katerynivka and Nove, a key point on the Russian bridgehead; Biletsky reported the fourth phase complete in mid-October. Ukrainian figures for the ground recovered vary widely — 176 km² claimed in late September, a more conservative 125–140 km² from Zelenskyy on October 4, and 277 km² across sixteen settlements in Biletsky's final tally. The Institute for the Study of War assessed that Russia lost about 256 km² in September while capturing about 176 km², a net loss of roughly 81 km²; Finland's Black Bird Group called the month Russia's largest net territorial loss since June 2023. Putin, by contrast, claimed 1,301 km² captured in September, a figure independent maps did not support. Lyman itself did not change hands.
Commanders