Ukraine’s Fortress Belt Is Under Growing Threat. Russia’s Slow Advance Puts Kramatorsk on Edge.

Ukraine's eastern defenses are coming under renewed pressure as Russian forces inch toward Kramatorsk, threatening a chain of fortified cities that has helped prevent Moscow from advancing deeper into the country.

The gains remain slow and costly, but the shift has eroded the optimism that followed Ukraine's territorial advances earlier this year and raised new questions about how long its remaining strongholds in Donbas can hold.

The pressure is already reshaping daily life in Kramatorsk. Iryna Rybakova, a press officer with Ukraine's 93rd mechanized brigade, told CNN that guided bombs and drones strike the city repeatedly, damaging homes, vehicles and public infrastructure. Nearly all its bridges have been destroyed, while the threat of drones has made even ordinary trips through the city dangerous.

Kramatorsk is not just another city on the front line. It is part of Ukraine's so-called fortress belt, a network of industrial centers that includes Sloviansk, Druzhkivka and Kostyantynivka. Their roads, railways and urban terrain provide a defensive barrier between Russian forces and the more open plains farther west. A breach could make it easier for Moscow to push deeper into eastern and central Ukraine, although such an outcome is far from inevitable.

According to the Institute for the Study of War, Russian forces advanced or infiltrated into approximately 124 square kilometers of Ukrainian territory in August, about one-quarter of the territory gained during the same month in 2025.

The pace is slow, and Western intelligence estimates cited by CNN suggest Russia is suffering roughly 40,000 casualties a month. Those figures underscore the enormous cost of Moscow's offensive, even as its incremental gains create mounting pressure on Ukrainian defenses.

Jennie Olmsted, a Russia analyst at ISW, told CNN that Russian forces are continuing infiltration operations and making gradual progress toward Sloviansk and Kramatorsk. She said the situation has shifted in Moscow's favor, but a rapid breakthrough remains unlikely.

The southern end of the defensive belt has already suffered a major setback. CNN reported that Kostyantynivka has effectively lost its operational value as a Ukrainian stronghold, although pockets of resistance remain in the city's north. The battle reflects a pattern of prolonged Russian assaults that destroy much of a city's infrastructure before Moscow gains control.

The military stakes are accompanied by a growing humanitarian crisis. Nearly 93,000 civilians, including more than 4,800 children, remain in the parts of Donetsk region controlled by Ukraine, according to the regional military administration. Evacuations are becoming increasingly difficult as mines and drones make roads unsafe.

Hennadiy Yudin, an officer with Ukraine's White Angels evacuation unit, told CNN that police can no longer drive into Dobropillya and nearby villages. Soldiers must bring residents out on foot before evacuation teams can collect them farther from the front. In Kramatorsk, Rybakova said the city continues to function, but the constant bombardment has eliminated its former role as a relatively safe place for exhausted troops to rest.

The battlefield deterioration comes as diplomacy remains stalled. U.S. envoys Steve Witkoff and Jared Kushner visited Kyiv on Sunday after talks in Moscow, but no breakthrough was announced. Reuters reported that the envoys hoped to revive negotiations, while Ukrainian President Volodymyr Zelenskyy emphasized the need for continued military and energy support ahead of winter.

Russian President Vladimir Putin continues to demand control over all of Donetsk and Luhansk. The Kremlin has claimed its forces are making tangible progress, but CNN said it could not independently verify Moscow's assertions about how soon its objectives might be achieved.

For Ukraine, the immediate challenge is preventing slow territorial losses from becoming a wider defensive collapse. Reuters reported Tuesday that Kyiv has appointed new commanders to strengthen its eastern defenses, while analysts expect intense fighting through September and October.