Ukraine said on Monday that Russia was preparing for a fresh wave of missile attacks on its energy grid that have plunged swathes of the country into the cold and dark.
A Ukraine military spokesman said a Russian warship capable of firing cruise missiles had recently deployed to the Black Sea with Kalibr-type missiles on board.
"This indicates that preparations were underway," said spokeswoman Natalia Gumeniuk.
"It's quite likely that the beginning of the week will be marked by such an attack," she added.
With temperatures dipping below zero, repeated Russian attacks have left Ukraine's energy grid teetering on the brink of collapse and disrupted power and water supplies to millions over recent weeks.
In its most recent barrage, Russia fired dozens of cruise missiles at targets across Ukraine last week, and an official in Kyiv said Monday that residents in and around the capital were still suffering disruptions as a result.
"Emergency electricity shutdowns are ongoing in the Kyiv region. About 40% is currently without power. These are the consequences of the massive rocket attack that happened last week," Governor Oleksiy Kuleba told local media.
President Volodymyr Zelensky cautioned in an address to Ukrainians late on Sunday that Russia was preparing new aerial attacks.
Moscow's forces would continue the campaign of systematic attacks "for as long as they have missiles," he said.
Zelensky added that the military was preparing itself, alongside Western allies, who have been delivering new air defense systems to Ukraine.
Russia has said it only targets military-linked infrastructural facilities and blamed the blackouts and their civilian impact on Kyiv's refusal to negotiate with Moscow, not on Russian missile attacks.
The Ukraine presidency said Monday that Russian strikes had left four people dead in frontline regions a day earlier.