Ukraine’s Vivaldi counteroffensive disrupts Russia’s plan to encircle Donetsk Fortress Belt – ISW

Operation Vivaldi has significantly disrupted Russia's plan to encircle the fortified "Fortress Belt" in Donetsk Oblast, according to the Institute for the Study of War (ISW). The counteroffensive, which began on September 15, has rendered Russia's encirclement efforts from the north and south unfeasible. Ukrainian forces have cleared 75 square kilometers of Russian troops and liberated Serednie, with the operation expected to have larger gains than initially disclosed.

Russian sources are now acknowledging the deterioration of their position in the area, with reports of shelling in Kolodyazi and a "coy acknowledgement" that Ukrainian forces have likely liberated the settlement. The gains have also disrupted Russian logistical support, forcing some elements to cross into Russia's Voronezh Oblast.

The counteroffensive's broader significance lies in its delay of Russia's planned offensive toward Sloviansk and the vulnerability of the northern flank of Russian forces. Despite setbacks, Russian forces continue to prioritize frontal attacks against the Fortress Belt and encirclement efforts from the southwest.