Russian forces continue grinding offensive operations in the Kostiantynivka sector of Donetsk Oblast, a key southern anchor of Ukraine’s defensive “fortress belt” shielding approaches to Kramatorsk and Sloviansk. Ukrainian General Staff reports from late September and early October 2026 document daily repels of 16–28 Russian assaults near the city and nearby settlements including Illinivka, Osykove, and Vilne, amid heavy use of glide bombs, drones, and artillery. Earlier 2026 advances featured Russian infiltrations and tactical gains that turned parts of the city into a contested gray zone, followed by disputed July capture claims that Ukraine rejected and partial Ukrainian clearances. Full seizure has not occurred despite Russia’s spring–summer priority on the axis, with Ukrainian forces retaining positions while both sides face logistics strain and high attrition in close-quarters fighting.