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Institute for the Study of War@TheStudyofWar · Sep 16, 2026

Key Takeaway: Ukraine’s Operation Vivaldi has achieved the operationally-significant objective of disrupting the…

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Summary

Ukraine's Operation Vivaldi has successfully disrupted Russia's plan to encircle Ukraine's Fortress Belt from the north, with Ukrainian gains north of Lyman making the Russian strategy unfeasible. Russian forces continue prioritizing frontal attacks from the south and southwest despite the failed Lyman offensive, possibly to maintain domestic propaganda narratives about advances in Donetsk Oblast.

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  1. #1

    Key Takeaway: Ukraine’s Operation Vivaldi has achieved the operationally-significant objective of disrupting the Russian effort to conduct a wide encirclement of Ukraine’s Fortress Belt. 🧵⬇️(1/3) Ukraine’s gains thus far north of Lyman have rendered unfeasible the already-unrealistic Russian plan to encircle the Fortress Belt from the north and south.

    Institute for the Study of War@TheStudyofWar · Sep 16, 2026

    NEW: The Ukrainian military gave its first explicit confirmation of ongoing Ukrainian counteroffensive operations against the Russian salient northwest of Lyman. The Ukrainian 3rd Army Corps conducted an intermediate-range strike campaign to interdict Russian logistics and degrade fuel supplies as part of Operation Vivaldi. Ukraine’s Operation Vivaldi has achieved the operationally-significant objective of disrupting the Russian effort to conduct a wide encirclement of Ukraine’s Fortress Belt. Other Key Takeaways: Ukrainian President Volodymyr Zelensky restated on September 15 Ukraine’s willingness to engage in a mutual ceasefire on energy targets with Russia amidst US President Donald Trump’s push for this ceasefire. The Kremlin continues to publicly and explicitly outline its continued commitment to its maximalist war aims in Ukraine and deflect from opportunities for de-escalation. The US Treasury Department announced on September 14 that it imposed additional sanctions against Russian state-majority owned bank VTB for its involvement in Iranian sanctions evasion and increasing Russian-Iranian bilateral trade. Ukrainian forces recently advanced in the Lyman direction and the Fortress Belt Outer Encirclement Effort. Russian forces launched 200 drones against Ukraine overnight. Ukrainian forces conducted a series of long-range drone strikes against oil, defense industrial, and military infrastructure in Russia.

  2. #2

    2/ Russian forces continue prioritizing attacks aimed at advancing frontally on the Fortress Belt from the south and encircling the Fortress Belt from the southwest over efforts to advance on the cities from the east, even though the Lyman effort has failed. The Russian military command may still be internalizing the loss of the Lyman salient and tactical initiative in the area or may seek to cut Ukrainian ground lines of communication (GLOCs) to the Fortress Belt from the west.

  3. #3

    3/ The Russian military command also likely seeks to achieve informational effects by continuing to make claimed or actual advances in Donetsk Oblast, Russia’s stated priority effort, that the Kremlin can portray as victories domestically and internationally. Ukraine’s ongoing counteroffensive undermines this Russian cognitive warfare effort, however, and will likely continue to do so as Ukrainian forces continue and later release more information about Operation Vivaldi.