Ukrainian forces hit two drone bunkers, two storage facilities and a Geran-5 launch pad at Russia's Tsymbulovo base overnight into Sept. 21, preliminary reports cited by WarTranslated indicated. The base in the Oryol region is a key launch site for jet-powered Shahed and Geran drones used against Ukraine.

Ukrainian drones also targeted Bashneft's refining infrastructure in Ufa, Bashkortostan, that morning, prompting a temporary suspension of local airport operations and a drone alert, WarTranslated reported. The city is a refining hub with capacity exceeding 23 million tons of oil a year. AMK Mapping reported a large fire after strikes on the Bashneft-Ufaneftekhim refinery.

The attacks followed a Sept. 20 Ukrainian barrage that damaged the Moscow Oil Refinery in Kapotnya. Mayor Sergei Sobyanin confirmed damage at the site, while Ukraine's General Staff said three processing units were hit. Russian authorities reported at least two deaths in the wider Moscow region during that attack, which coincided with the final day of parliamentary voting.