KYIV/NEAR DRUZHKIVKA, Ukraine, June 29 - Russian forces are methodically pressing into Kostiantynivka, a pivotal stronghold in eastern Ukraine’s so-called "fortress belt," long targeted by Moscow. While advances elsewhere along the roughly 1,200-km front have largely stalled, fighting has begun to encroach on the city itself, Ukrainian commanders said.
Senior Ukrainian officers reported last week that small groups of Russian soldiers are attempting to infiltrate the outskirts of Kostiantynivka, indicating the potential for close-quarters assaults in the near term. The city is the southernmost of four key settlements that form a defensive line central to Ukraine’s effort to hold the heavily industrialised Donetsk region.
Analysts note that the push toward Kostiantynivka underscores an enduring Russian manpower advantage even as Kyiv’s mid-range drone strikes on logistics have begun to degrade Russian capabilities. "The effect (of mid-range strikes) hasn’t been so great that it would have forced the Russians to suspend their offensive," said Emil Kastehelmi of the Black Bird conflict analysis team in Finland. "So even though Russia has been taking increasingly heavy losses in the rear, they are still able to continue their offensives, at least in certain sectors."
Securing Kostiantynivka would give Russian forces a staging point to move north along the belt, which now forms the central axis of Moscow’s campaign in the region. However, any such advance is expected to be difficult and costly for Russian units, potentially resembling other intense urban sieges fought in the east, where progress has frequently come at high human and material cost.
President Vladimir Putin has said Russia must control all of Donetsk before the war ends. Ukraine, after more than four years of combat, still retains about a fifth of the region.
"STAKES RISING EACH DAY"
Putin said last week Russia was close to capturing Kostiantynivka. The city’s pre-war population approached 70,000, a figure that has dropped to roughly 2,000, according to figures cited by officials. In rebuttal to assertions of an imminent fall, senior commanders of Kyiv’s 19th Army Corps described the Russian claim as exaggerated and said their forces are eliminating small Russian groups that have entered.
Maj. Gen. Viktor Nikoliuk, head of Ukraine’s eastern operational command, told Ukraine’s public broadcaster that Kostiantynivka could continue to hold given current allocations of manpower and supplies. The U.S.-based Institute for the Study of War assessed on June 23 that, although the tactical picture is deteriorating for Ukraine, the Russian infiltrations do not yet constitute "a rapid operational breakthrough."
Still, Ukrainian mapping analyst Ruslan Mykula of the DeepState open-source group warned that Russian attempts to envelop the city using pincer movements are steadily increasing the cost to Kyiv of defending Kostiantynivka. "A choice will have to be made: either raise the stakes or withdraw," he said. "And right now, the situation is such that the stakes are rising with each passing day." Emil Kastehelmi added that the city’s fall "seems to be more of a question of time."
Russian forces are also exerting pressure at the northern end of the fortress belt, where Sloviansk and Kramatorsk face frequent air and drone attacks from positions approximately 15 km (9 miles) away, according to reporting from the area.
Supply lines and contested routes
Ukrainian supply lines are under continuous pressure. Troops in the vicinity described artillery, drones and guided bombs battering infrastructure along the road north from Kostiantynivka, complicating movement and logistics. Reuters accompanied elements of the "Predator" rifle brigade, operating under the National Police, on patrol duty along the embattled route, which is tasked with countering drones and remotely dropped mines.
Anti-drone netting draped over the road was found with strands of fibre-optic cable used to guide first-person-view drones glinting in the sun. Ground robots ferrying food, water and supplies have become the primary method of delivery inside what troops call the "kill zone." Soldiers move quickly on quad bikes; the route is meanwhile too hazardous to use standard vehicles to evacuate the dead and wounded.
"Everything happens on foot," said 34-year-old serviceman Oleksandr Kosmin, describing conditions on the route.
Drone-infested skies and civilian toll
Civilian life in towns near the front is fraying under the strain. In Druzhkivka, about 12 km north of Kostiantynivka, residents are being forced to leave as fighting advances. On one street a husband and wife were found dead inside a van that had been struck by a Russian drone; white ribbons, intended to mark the vehicle as civilian, still fluttered on the roof.
"Why am I leaving? Because I’m scared. Drones are flying," said 59-year-old Larysa Sereda from inside a police evacuation van. She said she plans to return once the war ends: "I don’t want to stay in some strange place. The war will end, and I’ll come home." Her comments reflect the dilemma facing many civilians torn between immediate safety and the desire to return to familiar surroundings.
Operational strains on Russian logistics
The incremental Russian advances around Kostiantynivka are occurring even as the wider Russian war effort faces mounting pressures from Ukrainian strikes on supply routes to and from Crimea and longer-range attacks on the oil sector. Authorities installed by Russia on the occupied Black Sea peninsula have declared a state of emergency to address economic problems and have halted fuel sales to individuals and businesses, reflecting disruption in occupied areas.
On the battlefield at large, some analysts say Russian forces appear overextended and that many frontline assaults are limited in manpower. Mykula described assaults that often amount to just one or two soldiers. Nevertheless, Denis Pushilin, the Kremlin-appointed head of the Donetsk region, said Russia’s campaign to capture additional cities continues. "Talking about whether this is happening slowly or quickly isn’t really the point," he said, arguing that the advance remains underway.
As Kyiv and Moscow vie for control over townships and supply routes in Donetsk, the immediate trajectory around Kostiantynivka remains contested. Ukrainian commanders emphasize their ability to repulse small infiltrations, while analysts and Russian statements underscore continued pressure and a potential for protracted, high-cost fighting as forces try to secure or defend the city and the broader fortress belt.