For nearly three years, the mining town of Vuhledar has underpinned Ukraine’s defense of its southern Donbas region, the industrial heart of the country that has become a tableau of desolation and destruction.

Now the town, its rows of stark Soviet-style apartment blocks battered by the full force of Moscow’s arsenal, is on the verge of falling to Russian troops who have been grinding their way across the region in recent months, Ukrainian soldiers said.

On Monday, Russian forces moved into part of Vuhledar for the first time, hanging a flag over a ruined building, according to combat footage released by Russian forces and verified by military analysts. Last week, Ukrainian troops in the area said the Russians had been converging on the town from three directions.

The impending loss of Vuhledar highlights what has become a grim pattern in the war in eastern Ukraine, with Russia’s scorched-earth tactics and headlong assaults steadily eroding Ukrainian defenses with a string of strategic towns and cities falling like dominoes.

Defeat in Vuhledar would represent both a strategic loss for the Ukrainian military as its defensive lines buckle under months of relentless assault and a symbolic blow given the central role this town has played holding back the Russian onslaught.