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

Russia is intensifying its efforts to capture Kostiantynivka, a crucial city within Ukraine's eastern "fortress belt" in the heavily industrialized Donetsk region. While Russia's broader advances along the 1,200-kilometer front line have largely stalled, fighting is now seeping into Kostiantynivka itself.

Senior Ukrainian commanders reported last week that small groups of Russian soldiers are attempting to infiltrate the city's outskirts. This suggests that close-quarters assaults may follow. Kostiantynivka is one of four key settlements forming a defensive line central to Ukraine's strategy to retain control of the Donetsk region. Analysts note that Russia's persistent manpower advantage allows it to continue offensives in certain sectors, even while absorbing heavy losses in its rear areas, despite Ukraine's mid-range drone strikes on Russian logistics.

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The effect [of mid-range strikes] hasn’t been so great that it would have forced the Russians to suspend their offensive. 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.

Capturing Kostiantynivka would provide Russian forces a strategic foothold to advance north along the defensive line, which has become the central axis of their campaign. However, any such advance is expected to be protracted and costly, potentially mirroring the difficult sieges of cities like Pokrovsk and Avdiivka. President Vladimir Putin has declared Russia's intention to control all of Donetsk before the war concludes, though Ukraine still holds approximately one-fifth of the region after more than four years of conflict.

Last week, Putin claimed Russia was nearing the capture of Kostiantynivka, a city whose pre-war population of nearly 70,000 has dwindled to around 2,000. Ukrainian commanders from Kyiv's 19th Army Corps dismissed this as an exaggeration, stating their troops are effectively engaging small Russian groups that manage to enter the city. Maj. Gen. Viktor Nikoliuk, head of Ukraine's eastern operational command, indicated that Kostiantynivka could hold out at the current rate of manpower and resources. The US-based Institute for the Study of War assessed on June 23 that while the tactical situation is worsening for Ukraine, the Russian infiltrations are insufficient for a "rapid operational breakthrough." Nevertheless, Russia's pincer movements around the city are steadily increasing the costs for Kyiv.

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a rapid operational breakthrough