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ISW also assessed that Putin seeks to speed up the process of annexing captured Ukrainian territories, which would then be used to justify nuclear threats - as "defending Russian territorial integrity."
"Putin may believe that the threat or use of nuclear weapons would restore Russian deterrence after his disastrous invasion shattered Russia's conventional deterrent capabilities," the report reads.
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"Ukraine and its Western partners may have a narrowing window of opportunity to support a Ukrainian counteroffensive into occupied Ukrainian territory before the Kremlin annexes that territory."
U.S. National Security Council spokesperson Jon Kirby earlier said that intelligence points towards the Kremlin rushing to "legitimize" its territorial gains in Ukraine via a series of sham referenda, mirroring Russia's 2014 annexation of Crimea.
Read also: Putin is inching towards his nukes, threatening to annihilate the world if he fails to capture Ukraine, says foreign affairs expert
Ukrainian military intelligence warned on June 23 that Russia is planning to stage these "votes" in Kherson and Zaporizhzhya oblasts by September 11.