The dealbreaker The Donetsk region’s ‘fortress belt’ blocks Russian troops from sweeping into central Ukraine. Putin wants Kyiv to surrender it.
In the days since Vladimir Putin and Donald Trump’s Alaska summit, the world’s attention has turned to the portion of the Donetsk region that Kyiv still controls — and that Putin wants it to give up. This territory contains Ukraine’s “fortress belt,” a 31-mile stretch of defensive structures and fortified settlements that’s been built up over more than a decade. Western media outlets have argued that this belt is both the motivation for Putin’s demands and the reason his proposal is a non-starter for Ukraine. Meduza assesses these claims and explains the military and political significance of the “fortress belt.”
On August 15, Russian President Vladimir Putin and U.S. President Donald Trump met in Alaska for their first in-person talks on the war in Ukraine. According to Reuters, Putin used the meeting to lay out his terms for ending the invasion. In addition to demanding official status for the Russian language and permission for the Russian Orthodox Church to operate in Ukraine, Putin sought sanctions relief for Russia, recognition of Crimea as Russian territory, and the full withdrawal of Ukrainian troops from the eastern Donetsk and Luhansk regions. In exchange, Moscow is prepared to freeze the front line in the Kherson and Zaporizhzhia regions and withdraw from Ukraine’s Sumy and Kharkiv regions.
Calculations by Reuters based on open-source data show that as of mid-August 2025, Russian forces occupy 19 percent of Ukraine, including 74 percent of the Kherson and Zaporizhzhia regions. The Luhansk region is almost entirely under Russian control, but in the Donetsk region, Ukrainian forces continue to hold significant territory. Ukraine controls roughly a quarter of the region — about 6,600 square kilometers (over 2,500 square miles).
President Volodymyr Zelensky has repeatedly stated that Ukraine will not “gift” its land to Russia. The Financial Times reports that, behind closed doors, the Ukrainian leader may be open to a “digestible compromise” with Moscow involving a freeze along the current front line, but he considers a voluntary withdrawal from the still-unoccupied parts of Donbas an “impossible” step.
Full control of Donbas is widely regarded as one of Putin’s key demands. And this isn’t simply because Russia formally annexed the entire Donetsk and Luhansk regions back in 2022 — after all, it also claimed the Kherson and Zaporizhzhia regions at the same time, and according to media reports, Moscow appears willing to freeze the front line in those southern regions.
The Economist suggests the real reason lies in Ukraine’s “fortress belt” in northern Donetsk. This 50-kilometer (30-mile) line of defenses, stretching from Sloviansk and Kramatorsk to Druzhkivka and Kostyantynivka, is a major barrier to Russia not only seizing the whole of Donbas but also threatening other Ukrainian regions.
The “fortress belt” is a densely built-up, urbanized area that hampers troop advances. Its construction began in 2014, after Russia annexed Crimea and launched its war in Donbas. After the fall of Bakhmut in 2023, Ukraine further strengthened the area with bunkers, trenches, minefields, and anti-tank obstacles.
Former Ukrainian Defense Minister Andrii Zahorodniuk told The Economist that Ukraine has made “massive” investments in these fortifications. The magazine wrote that Kramatorsk and Sloviansk have become “bastion towns” — logistical hubs for Ukraine’s military and military production centers. Nico Lange, a former chief of staff at Germany’s defense ministry, noted that capturing the belt” would take Russia years and cost enormous human and material losses.
On the other hand, Moscow could opt not for direct assaults on Kramatorsk and Sloviansk but for encircling the towns, forcing Ukrainian troops out of their positions. Russian forces have already taken other heavily fortified strongholds, such as Avdiivka.
Surrendering the “fortress belt” would be problematic for Ukraine for several reasons. First, and perhaps foremost, many Ukrainians would see it as a betrayal of all of the sacrifices their compatriots have made. Second, the Ukrainian army can’t simply withdraw and build new fortifications elsewhere — this takes money and time. Third, in Russia’s hands, the fortified area would be a natural launchpad for further aggression.
“It’s not just trenches,” Elina Beketova, a fellow at the Center for European Policy Analysis (CEPA), told The Independent. “It’s a deep, layered defence with bunkers, anti-tank ditches, minefields, and industrial areas built into the terrain. The area includes dominant heights, rivers, and urban zones that make it extremely hard to capture.” If these defenses were to fall, she warned, the front line would shift 80 kilometers (50 miles) westward, granting Russia access to “open ground — flat steppe with no natural barriers — giving it a direct path towards Kharkiv, Poltava, and Dnipro.”
The Kyiv-based outlet The Counteroffensive noted that the fortifications that make up the fortress belt were built by both military servicemen and civilian workers. It referred to these defenses as “the top prize Putin wants to claim in negotiations to end the war.” The Wall Street Journal also reported that the reason Putin is insisting on the Donetsk region is that “Ukraine created what essentially is a 31-mile fortress belt of heavily fortified cities, towns, and defensive embattlements” there.
However, Meduza’s own analysts argue that the “fortress belt” is unlikely to be one of the main reasons behind Moscow’s demands for the entire Donbas region. According to them, Russia’s ongoing offensive operations aimed at these fortifications is driven more by political considerations. Namely, to destabilize Ukraine and weaken Zelensky by forcing Ukrainian forces to withdraw from unoccupied areas, and to justify the war to Russians domestically through rhetoric about “protecting Russians in Donbas.”
At the same time, Meduza’s experts note, Kyiv’s refusal to cede territory leaves Moscow with the option of forcibly taking the “fortress belt.” Judging by the current pace of the Russian advance and the balance of forces, this could realistically happen by mid-2026. Militarily, capturing the “fortress belt” would be easier for Russia than launching assaults on still-unconquered parts of the Kherson and Zaporizhzhia regions.
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