What Happened: In calls with the British, French, Turkish and U.S. defense ministers, Russia's Defense Minister Sergei Shoigu conveyed concerns that Ukraine might use a "dirty bomb" in its counteroffensives against Russia, Reuters reported Oct. 23. In a statement, the United States, United Kingdom and France rejected Russia's allegations, while Ukrainian President Volodymyr Zelensky said the accusation was a sign that Moscow was planning such an attack itself and would blame Ukraine.

Why It Matters: Shoigu's accusations lay the groundwork for Russia to blame Ukraine for any radiological incident that would result from Russia using a dirty bomb, so Moscow will continue pushing the alleged dirty bomb threat to mitigate reputational damage if it decides to make such a move. These efforts to create plausible deniability mean Russia remains more likely to use a dirty bomb against Ukraine than a tactical nuclear weapon. Moscow's allegation could also be a sign that it is preparing to strike Ukrainian nuclear facilities and blame Ukraine for any resulting radiological leakage. Regardless, Moscow's talk of a dirty bomb is new and intended to fuel war fatigue in the West and to fabricate a justification for Russian escalation to stop Ukrainian gains on the battlefield.

Background: On Oct. 24, Ukrainian Foreign Minister Dmytro Kuleba asked the International Atomic Energy Agency to immediately send experts to nuclear facilities in Ukraine.