ISW: Russia Initiates Spring-Summer 2026 Offensive Against Ukraine's 'Fortress Belt' in Donetsk Oblast
The Institute for the Study of War assessed that Russian forces have initiated their Spring-Summer 2026 offensive targeting Ukraine's 'Fortress Belt' anchoring Slovyansk and Kramatorsk in Donetsk Oblast. The operation remains in its shaping phase with probing actions and intensified strikes across multiple axes. Weekly Russian casualties approximately doubled versus winter levels — 405 casualties from ~500 personnel in a single March 19 assault. Russian units from the 1st Guards Tank Army and 20th Combined Arms Army face reduced training cycles (one week vs. one month) and depleted combat power. Ukrainian forces demonstrate tactical adaptation, downing two Ka-52 helicopters within two days. Ukraine's MoD reports cumulative Russian losses of ~1,288,850 personnel, 11,794 tanks, and 192,869 UAVs since February 2022.
Prior digest reported Russia launching spring offensive with battalion-sized mechanized assaults. ISW now confirms this is the formal Spring-Summer 2026 campaign targeting the Fortress Belt. Weekly casualty doubling vs. winter indicates major commitment despite depleted training cycles.
2 sources
- Russia's Spring Offensive Begins Against Ukraine's Fortress Belt: ISW -
Small Wars Journal - Total Russian combat losses in Ukraine as of March 23, 2026 -
Ukraine Ministry of Defence