Russia claimed the preparations are in response to Ukraine's repeated attacks.Russian forces have begun preparations for what Moscow described as “massive strikes” against Ukraine’s energy facilities in response to attacks on Russian civilian infrastructure and the country’s energy sector, Russia’s Defence Ministry said Sunday.The ministry said Russian forces had also continued overnight to carry out coordinated strikes against facilities linked to Ukraine’s defence industry, reported Reuters.The latest warning comes a day after a Russian strike on Ukraine’s Bucha district near Kyiv killed at least 37 people, according to Ukrainian officials. The attack damaged at least 50 residential buildings and triggered a large fire that spread to several homes and a restaurant, officials said.Ukrainian President Volodymyr Zelenskyy said a warehouse in the village of Myla was hit and followed by an explosion. He said authorities had opened criminal proceedings over suspected official negligence, alleging that ammunition had been stored near residential areas despite regulations prohibiting it.The attack came as Kyiv faced a third consecutive day of near-continuous Russian air raids, disrupting daily life and economic activity in the capital.Russia’s latest threat raises the prospect of further attacks on Ukraine’s power infrastructure, which has repeatedly been targeted during the more than four-year-old war. Both sides have increasingly used long-range missiles and drones to strike military, energy and infrastructure targets far behind the front lines.Russia launched its full-scale invasion of Ukraine in February 2022, and the conflict has since evolved into a prolonged war marked by repeated aerial attacks, territorial battles and strikes on critical infrastructure.