Russia is trying to cut off two of Ukraine's biggest remaining strongholds in the east before it ever storms them, according to the Institute for the Study of War (ISW). The think tank finds Moscow reviving a months-long air campaign against supply lines — the same method that preceded its 2025 advances elsewhere in eastern Ukraine. This time, the target is the Fortress Belt, and the effort leans more heavily on glide bombs than before.

Russia dusts off its 2025 logistics playbook

Through 2025, Russian forces ran long campaigns of drones, glide bombs, and missiles to sever Ukrainian supply lines before pushing near Pokrovsk and Huliaipole. ISW calls this battlefield air interdiction (BAI) — using airpower to strike rear targets behind the front and choke an enemy's logistics. Now the same approach has moved north, ISW assessed, aimed at Sloviansk and Kramatorsk, the twin cities anchoring the top of the Fortress Belt. The goal is to isolate the defenders there from steady resupply. Ukrainian and Russian commentators alike have described the strain, noting that nighttime logistics runs into the two cities have become hard to pull off.

The target list: bridges, rails, and the roads between

Russia has increasingly gone after the locomotives that keep Ukrainian supplies moving, and reportedly handed troops 1,000 Molniya loitering munitions in July 2026 with orders to intensify strikes near Kramatorsk. It has also begun hitting major bridges. Geolocated footage posted on 2 August showed a heavily damaged crossing over the Kazennyi Torets River in eastern Sloviansk. The bridge linked the city to the highway leading to Kramatorsk.

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More glide bombs, fewer drones

This year's campaign appears to lean more heavily on glide bombs than the 2025 versions did, ISW found, with many reports of guided glide-bomb strikes on Sloviansk, Kramatorsk, and surrounding settlements over recent weeks. ISW assessed that Russia may be reaching for these heavy bombs because Ukrainian jamming and interceptors have blunted its capacity to field drones as widely as before. The bombs do more than break fortifications. ISW noted the strikes reduce cities to rubble that Russian troops then use as cover, as they have in Kostiantynivka.

A slow build, not a quick breakthrough

The point of the campaign, ISW assessed, is to shape the battlefield for a future offensive against Sloviansk and Kramatorsk — not to seize them now. ISW does not expect Russian forces to reach or push through the cities soon. Russian troops have been infiltrating Kostiantynivka for months without capturing it, despite Russian claims otherwise. Russia's 2025 campaigns needed months to prepare later advances, and ISW expects this one to move just as slowly.

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At the same time, Ukraine's Joint Forces spokesman Viktor Trehubov gave a similar read on Lyman. He told national television that Russia wants the town as a launchpad toward Sloviansk and Kramatorsk. But he said Russian forces still cannot dig in there, and Ukraine's growing drone advantage is tipping the fight toward Kyiv.

Russian troops are working deeper into Ukraine's last fortified cities in Donetsk Oblast, pushing infantry into Kostiantynivka while wrecking the towns behind it, the Ukrainian monitoring and analytical project DeepState reported. The US-based think tank Institute for the Study of War (ISW) recorded fresh Russian movement inside the city over the same days.

Kostiantynivka: Russian infantry keeps slipping in

Russian forces keep up constant infiltration attempts on Kostiantynivka, DeepState said. Their aim is to entrench inside the city, mass infantry there and take control of the ground. One of their main tasks is to take control of the part of the city between the settlements of Illinivka and Novodmytrivka. If Russian troops take Novodmytrivka, the entire Ukrainian grouping defending Chasiv Yar faces encirclement, DeepState noted. Supply into Chasiv Yar has been difficult for a long time, because Russian drone numbers hand Moscow the advantage in the air. Alongside the infantry, Russian forces use artillery and guided glide bombs to destroy the city.

ISW assessed on 28 July that Russian forces recently advanced in Kostiantynivka and kept up infiltration missions inside it. Geolocated footage from 27 July points to a Russian advance in the city's west, ISW said. Video published a day later shows Ukrainian troops hitting Russian positions in the north and center of Kostiantynivka, after what ISW assesses were infiltration missions.

Unnamed soldiers from units defending the city told Hromadske that the situation there is getting worse. Ukraine's General Staff counted 31 Russian attacks on the Kostiantynivka axis over the past day.

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Druzhkivka and the towns behind the front are turning to ruins

The whole agglomeration around Kostiantynivka is suffering. DeepState said Druzhkivka and neighboring Oleksiievo-Druzhkivka are gradually turning into ruins under constant shelling, and staying there is extremely dangerous. Russian forces fired 1,243 times at the front line and residential areas of Donetsk Oblast on 28 July, Ukraine's National Police recorded.

Russian pressure is rising on the stretch running roughly from Yampil to Minkivka further north, which may become the next main axis after Kostiantynivka, DeepState said. Russian artillery is already destroying mine barriers along the routes it would use, and Russian drones are working against Ukrainian logistics there.

Sloviansk and Kramatorsk under fire 40 km deep

Russian forces are leveling Sloviansk and Kramatorsk—the northern anchors of the Fortress Belt—with guided glide bombs, rocket artillery, Shahed attack drones and small first-person-view drones that hunt people and cars in the streets. DeepState noted that Russian fire control runs about 40 km deep from the contact line. The agglomeration is gradually becoming an isolated place, where travel will soon be possible only out of critical necessity, in order to fight.

ISW noted that Ukrainian troops have recently advanced farther south, toward Huliaipole in Zaporizhzhia Oblast. A Russian milblogger acknowledged the Ukrainian gains near the town on 28 July.