Reporting from near Lyman in eastern Ukraine, the BBC described commanders watching a live battlefield feed in a bunker as a Russian drone crossed the screen. One commander called in a Ukrainian drone to bring it down and warned soldiers crossing open ground below of the threat.
Kyiv says Operation Vivaldi, named for the four seasonal movements of the composer's violin concerto, has liberated 277 square kilometres of territory and blunted a Russian pincer movement that threatened to encircle the Fortress Belt cities still under Ukrainian control.
Ukraine claims it has inflicted heavy losses, including 8,000 Russian casualties in Vivaldi alone and close to 50,000 along the front in September, while suffering few casualties in return. These figures could not be independently verified.
The offensive is unfolding even as Russia pummels Ukraine from the air, crippling its energy infrastructure and killing scores of civilians, the BBC reported.
The operation has also thrown a spotlight on Ukraine's reliance on Western technology. This week Kyiv said vital Starlink satellite technology had restrictions imposed without warning. Elon Musk, who created Starlink, suggested the order may have come from the US government.
The Institute for the Study of War reported that pro-Russian military bloggers had acknowledged the Ukrainian advances and expressed fears this could lead to further Russian losses. No Russian official has publicly acknowledged the gains, and a Russian defence ministry briefing was cut off in the BBC dispatch.