ISW Russian Offensive Campaign Assessment, September 20, 2026

Key Takeaways from the ISW: Ukrainian forces conducted their largest combined missile and drone strike package against strategic targets in Moscow Oblast on the night of September 19 to 20, ahead of the final day of voting in the Russian State Duma elections. Russia’s failure to defend against the Ukrainian strikes prompted discontent among Russians, including in the ultranationalist information space, as the State Duma elections concluded. The Kremlin is presenting the initial and pre-determined September 18 to 20 State Duma election results as confirmation of Russian society’s broad support for the war effort in Ukraine despite the ruling United Russia Party’s exit numbers being granted a comparatively conservative margin. Numerous sources, including domestic Russian election observers, reported large-scale election violations and manipulation of the vote count in the September 18 to 20 voting period. Ukraine’s 3rd Army Corps publicized details on the second phase of Operation Vivaldi in the Lyman direction, which included liberating Shandryholove, Derylove, and Drobysheve (all northwest of Lyman). The Russian Federal Security Service (FSB)’s St. Petersburg and Leningrad Oblast Border Directorate published an order closing the Russian side of the border opposite Narva in northeastern Estonia from September 16 to 26. Neither Ukrainian nor Russian forces advanced. Ukrainian forces conducted a long-range strike against a likely Russian energy facility on the night of September 19 to 20. JOIN US ON TELEGRAMFollow our coverage of the war on the @Kyivpost_official. See the original here.