Kostiantynivka is one of Ukraine’s “Fortress Belt cities” Russia demands. It may fall by end of summer 2026, says observer

Russian forces may capture Kostiantynivka in Donetsk Oblast by the end of summer 2026, Ukrainian military observer Denys Popovych said on Radio NV. The warning comes as DeepState analysts have documented the Russian conversion of Kostiantynivka into ruins, and as Russian forces continue to consolidate in Pokrovsk and Myrnohrad.

Popovych says Russia could capture the city despite what he himself characterizes as the broader operational failure of Russia's spring-summer offensive.

Russian success would come even as Ukraine's deep-strike envelope reaches 1,800 km into Russia and the "Logistics Lockdown" campaign degrades Russian rear-area infrastructure. 

Pokrovsk tactic that may be repeated

"We are now talking about the general failure of the spring-summer phase of Russian army offensive actions in the east and the south. But the prize in the form of Kostiantynivka they may take during this summer," Popovych said.

He added that Russian occupiers in Kostiantynivka are attempting to apply the same tactic they used in Pokrovsk: entrenching on the outskirts, then progressively infiltrating into the city itself by occupying multi-story buildings.

"Those enemy infiltration groups are being destroyed. But the question is whether we have enough resources to destroy every group," he continued. 

According to the expert, if one of them holds, settles in, and Ukraine doesn't notice it, then that chain, that path, will be trampled by the Russians.

"They will spread further through the city. This is the standard scenario the Russians have used during those cities that held defense for a long time," Popovych believes.

Russian drone crews may take same actions used in Pokrovsk, but now in Kostiantynivka

After the seizure of Pokrovsk and Myrnohrad per DeepState's assessment, Russian forces continue to build up forces inside them, particularly drone crews who have taken control of urban airspace. 

"The enemy is establishing itself in the cities and currently maintains the active task of advancing into the depths of our defense," DeepState noted in its analysis.

The combination of Russian drone control of urban airspace in already-captured cities and the slow-infiltration approach for the next target city is what makes Kostiantynivka's risk, as Popovych described, not hypothetical. Russia has demonstrated that the tactic produces results, slowly, against cities that hold out for extended periods.