Russia pounds on the gates of Ukraine's 'fortress belt'

Russia is grinding its way into Kostiantynivka, a key stronghold in Ukraine’s eastern “fortress belt” long coveted by the Kremlin, even as its gains across the rest of the 1,200-kilometre front line have largely stalled. Fighting has begun to seep into the city itself. Small groups of Russian soldiers are attempting to infiltrate its outskirts, senior Ukrainian commanders said last week, suggesting close-quarters assaults could follow. Kostiantynivka is the southernmost of four key settlements forming a defensive line central to Ukraine’s effort to hold the heavily industrialised Donetsk region. The push towards it underscores Moscow’s enduring manpower advantage, even as Ukrainian mid-range drone strikes on logistics have weakened its fighting capabilities, analysts said. “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.” Occupying Kostiantynivka would provide Russian forces a foothold from which to move north along the belt, now the central axis of their campaign. But any advance would likely be long and bloody for its forces, in a possible echo of other costly sieges of eastern cities like Pokrovsk and Avdiivka. President Vladimir Putin has insisted Russia must control all of Donetsk before the war ends. Ukraine still holds around a fifth of the region after more than four years of fighting. ‘Stakes rising each day’ Putin said last week Russia was close to capturing Kostiantynivka, whose pre-war population of nearly 70,000 has fallen to around 2,000. In comments to Ukrainian media, senior commanders of Kyiv’s 19th Army Corps dismissed that claim as an exaggeration and said their troops were picking off small groups of Russians that had managed to enter. Servicemen