Tuesday morning's massive barrage of drones and missiles launched by Russia came despite ongoing talks between US, Ukrainian, Russian and European officials.
The US-led shuttle diplomacy has picked up pace as the war has dragged on, much to the apparent frustration of Donald Trump, who famously vowed to end the war within his first 24 hours in office.
Trump's special envoy Steve Witkoff, and Trump's son-in-law Jared Kushner, have been meeting separately with Russian and Ukrainian negotiators to discuss revisions to a US peace proposal.
Here's what you need to know about the talks to end Russia's nearly four-year war: To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video
Ukraine's Prime Minister Yulia Svyrydenko has condemned Moscow for the "deliberate and cynical" attack on the eve of Christmas.
"While people were preparing for the holidays, the enemy [is] trying to leave Ukrainian families without electricity, heat, and a sense of safety," she said in an online post.
Svyrydenko said energy infrastructure in the west of the country was "hit the hardest."
Emergency power cuts were being scheduled because of the damage.
"They will be lifted as soon as the energy system is stabilized," she said, adding that work to restore power "as quickly as possible" was underway.
Russia's "massive attack" overnight across Ukraine has killed at least three people, Ukraine's President Volodymyr Zelenskyy said Tuesday morning.
A four-year-old child was killed in a drone strike on a residential building in the Zhytomyr region, west of Kyiv. Two other deaths — one in Kyiv and another in Khmelnytskyi — were also confirmed, Zelenskyy said on X.
Ukraine's president said the attack primarily targeted the country's energy sector and "essentially the entire infrastructure of daily life."
Zelenskyy said the strikes, which come as officials from Ukraine and Russia meet separately with US mediators for peace talks, send "an extremely clear signal about Russia's priorities."
"An attack ahead of Christmas, when people simply want to be with their families, at home, and safe. An attack carried out essentially in the midst of negotiations aimed at ending this war," Zelenskyy said.
The president repeated his call for action from Ukraine's Western allies, saying Moscow needs to be "pushed toward peace and guaranteeing security."
He urged for more deliveries of air defenses as well as funding to procure weapons and ensure energy supplies.
Poland and its allies have deployed aircraft to ensure the safety of Polish airspace after Russia launched airstrikes targeting western Ukraine.
"Fighter jets have been scrambled, and ground-based air-defense systems as well as radar reconnaissance systems have been put on heightened readiness," the operational command of Poland's armed forces said in a post on X.
"These actions are preventive in nature and are aimed at securing and protecting the airspace, especially in areas adjacent to the threatened regions."
Poland, a NATO member, shares a border of some 530 kilometers (330 miles) with Ukraine.
Russia launched an overnight barrage of drones and missiles on 13 regions across Ukraine, president Volodymyr Zelenskyy has said.
The strikes have killed at least three people and forced large-scale power cuts, with Ukrainians gearing up for Christmas amid freezing winter temperatures.
Russia's full-scale invasion of Ukraine has now stretched for nearly four years.
Moscow has continued to pummel Ukraine in recent days, despite US President Donald Trump claiming on Monday that the peace talks to end the conflict are "going OK."
Stay tuned as DW brings you the latest developments as well as analysis and background, from Russia's war in Ukraine.