Ukraine’s Vivaldi Counteroffensive Shatters Russia’s Donetsk Encirclement Plan

Key points

• Ukraine’s 3rd Army Corps reclaimed approximately 175-176 square kilometers of territory in the Lyman direction, eliminating a Russian salient that threatened the Fortress Belt cities of Sloviansk and Kramatorsk.
• The collapse of the northern pincer has fundamentally disrupted Russia’s 2026 campaign to encircle the Fortress Belt, forcing a reevaluation of military strategy and likely delaying any attempt to seize the region by force.
• Russian forces continue to prioritize the Dobropillya direction to attempt a southwestern encirclement, but face severe logistical and manpower constraints that limit their ability to achieve operational maneuver.
• Russian military and political leadership, including President Putin, continue to make false claims of territorial control, such as asserting control over Svyatohirsk and parts of Kramatorsk, despite Ukrainian counterattacks pushing the frontline significantly east.
• Ukraine has restructured its command in Donetsk Oblast, replacing the Eastern Group of Forces with the Azov and Center Groups of Forces to optimize defense of the Fortress Belt and improve command and control.

Background

The Fortress Belt, comprising Sloviansk, Kramatorsk, Druzhkivka, and Kostyantynivka, has been a key defensive line for Ukraine since 2014. Russian forces have attempted to seize these cities multiple times since 2022, including failed direct assaults and flanking maneuvers via Izyum. Operation Vivaldi, which began in May 2026, represents a significant Ukrainian counteroffensive aimed at disrupting Russian advances and reclaiming lost territory.

How outlets are covering it

The Institute for the Study of War (ISW) emphasizes the operational defeat of the Russian northern pincer and the fundamental disruption of the encirclement plan, noting that Russian forces are unlikely to seize the rest of Donetsk Oblast in the short term. Al Jazeera highlights the human cost of the conflict, including civilian casualties from Russian strikes, and notes that Ukraine’s counteroffensive has reclaimed 175 square kilometers. The Center for European Policy Analysis (CEPA) focuses on the role of operational secrecy and robotic warfare in Ukraine’s success, noting that Russian commanders’ tendency to lie about battlefield realities allowed Ukraine to maintain surprise. All sources agree that Operation Vivaldi has significantly disrupted Russian plans, but ISW and CEPA provide more detailed analysis of the military and strategic implications, while Al Jazeera focuses on the humanitarian impact and Russian civilian targeting.

Why it matters

The success of Operation Vivaldi demonstrates Ukraine’s ability to disrupt Russian offensive plans and reclaim lost territory, challenging Russian claims of inevitable victory in Donetsk Oblast. The disruption of the encirclement plan forces Russia to rethink its military strategy and may delay any attempt to seize the Fortress Belt. The continued false claims by Russian leadership highlight the disconnect between battlefield realities and official narratives, which may impact Russian military planning and morale.

What to watch

Russian forces are likely to continue prioritizing the Dobropillya direction to attempt a southwestern encirclement, but face severe logistical and manpower constraints. Ukraine may continue to counterattack and contest the operational initiative in Donetsk Oblast, while Russian leadership may face pressure to order a massive mobilization to restore its ability to seize and hold the initiative. The long-term implications of Operation Vivaldi remain unclear, but the operation has significantly disrupted Russian plans and may delay any attempt to seize the Fortress Belt.