Russian forces infiltrate Kostyantynivka, raising concerns over Donbas front

Russian troops have moved into the eastern Ukrainian city of Kostyantynivka and are working to surround it, Ukrainian sources told the BBC. The city, described as a gateway to the wider Donbas area, now lies in a contested "grey zone" with no clear control.

A Ukrainian drone operator, who asked to remain unnamed, said Russian units are slipping into positions behind Ukrainian lines, making urban clearance operations difficult. Brigadier General Oleksandr Bakulin, commander of Ukraine's 19th Corps, said the situation remains under control and that Russian forces have not achieved success, while acknowledging about 130 Russian soldiers are present in the city.

Russian defence officials claim their troops have rapidly advanced in the south-western part of Kostyantynivka and have encircled Ukrainian units. Ukrainian officers, also speaking anonymously, said Russian forces are progressing slowly, sometimes only a few metres per day, but continue to amass personnel inside the city.

Both sides reported increased drone activity. Ukrainian crews focus on targeting Russian infantry, while Russian pilots have prioritized destroying Ukrainian drone launch sites. The Ukrainian pilot noted that Russian forces rely on artillery, multiple-rocket launchers and aviation for ground attacks, limiting the drones' ability to intervene.

The development follows a pattern observed in other eastern Ukrainian cities, where Russian troops advance along flanks to cut off supply routes. In recent days, the Russian defence ministry announced the capture of villages west of Kostyantynivka, a move that coincides with heightened Ukrainian strikes on Russian oil refineries and supply lines to Crimea.