Russia launched the "most powerful" attack so far this year on Ukraine's battered energy facilities overnight, Kyiv has said, leaving hundreds of thousands without heating in glacial temperatures ahead of talks to end the four-year war.
Russia's strikes hit as temperatures dropped to their lowest since the start of the war in February 2022 and damaged an iconic Soviet-era WWII monument.
They came a day before Ukrainian and Russian negotiators were due to meet for a second round of talks in Abu Dhabi.
"Taking advantage of the coldest days of winter to terrorise people is more important to Russia than turning to diplomacy," Ukrainian President Volodymyr Zelensky said, denouncing the attack.
NATO chief Mark Rutte arrived in Kyiv on an unannounced visit, laying flowers with Mr Zelensky at a Kyiv memorial to killed soldiers.
He said Russia's overnight attacks did not suggest Moscow was serious about making peace, as the United States pushes talks to stop the fighting.
"Direct talks are now underway and this is important progress. But Russian attacks like those last night, do not signal seriousness about peace," Mr Rutte said in an address to Ukraine's parliament.
Mr Rutte said he was urging NATO countries to "dig deep into their stockpiles" to provide more urgently needed air defences to Ukraine as it struggles to stave off Moscow's bombardments.
The head of the Western military alliance insisted that its "attention has not been diverted" from supporting Kyiv despite a crisis over US demands on Greenland.
Mr Rutte said European members of NATO were willing to provide strong guarantees and deploy forces to Ukraine to make sure any ceasefire was enduring.
"The security guarantees are solid, and this is crucial - because we know that getting to an agreement to end this terrible war will require difficult choices," he said.
"Ukraine needs to know with absolute certainty - that whatever sacrifices you've made, the lives you've lost, the devastation you've endured - will not be at risk of repetition."
EU chief Ursula von der Leyen will also visit Ukraine to mark four years since the start of Russia's full-scale invasion this month, her spokeswoman said.
"It will be a renewed and reiterated sign of the solidarity of the European Union with Ukraine and of our determination and unity in the face of Russia's continued aggression," EU spokeswoman Paula Pinho told journalists.
Residents take shelter at Kyiv metro station as officials say city under missile attack
Meanwhile, AFP journalists heard explosions across the capital overnight and residents in over 1,000 buildings woke to find their heating cut off as temperatures dipped towards -20C.
Some residents gathered around a damaged building, stepping over creaking debris and a thick layer of ice coating the ground.
"Our windows are broken and we have no heating," Anastasia Grytsenko said, "we don't know what to do. Everyone is confused".
The Kremlin had last week said it agreed to a US request not to strike Kyiv for seven days, ending Sunday.
Ukraine had not reported large-scale Russian attacks on the capital last week, while reporting continued attacks in other parts of the country.
"Several types of ballistic and cruise missiles, as well as drones, were used to strike high-rise buildings and thermal power plants," Energy Minister Denys Shmygal said.
"Hundreds of thousands of families, including children, were deliberately left without heat in the harshest winter frosts," he added.
Today's strike on Ukraine's battered energy facilities was "the most powerful" since the start of 2026, the country's largest private energy provider DTEK confirmed.
Ukraine's air force said Russia had attacked with 71 missiles and 450 attack drones.
Five people were wounded in the capital, officials said, adding that thousands were without electricity.
'Symbolic and cynical'
The base of the city's towering Soviet-era Motherland statue was damaged.
"It is both symbolic and cynical: the aggressor state strikes at a place of remembrance of the struggle against aggression in the 20th century, repeating its crimes in the 21st century," Culture Minister Tetyana Berezhna wrote on social media.
Russian strikes had this month repeatedly cut power and heating to tens of thousands of homes - with Kyiv and its European allies accusing Moscow of deliberately freezing Ukraine's population.
Strikes also hit Ukraine's second-largest city, Kharkiv, temporarily cutting heating to some 100,000 subscribers.
The hours-long attack targeted energy infrastructure and aimed to "cause maximum destruction... and leave the city without heat during severe frost", Kharkiv Governor Oleg Synegubov wrote on Telegram.
Authorities had to cut heating to more than 800 homes to prevent the wider network from freezing, he said, urging people to go to round-the-clock "invincibility points" around the city if they needed to warm up.
Overnight temperatures plunged to -19C in Kyiv and sank as low as -23C in Kharkiv.
US pushes for deal
Russian occupational authorities in southern Ukraine said that Ukrainian shelling had killed three people in the town of Nova Kakhovka.
Kremlin-installed authorities said the shelling hit a municipal building and a fruit shop.
"There are dead: three people, including an employee of the administration," Vladimir Saldo, the Moscow-backed head of the Russian-controlled part of the Kherson region said.
Nova Kakhovka fell to Russian forces in the first days of their 2022 invasion. The US has sought to craft a settlement between the two sides, but the first round of trilateral talks held in Abu Dhabi last weekend failed to yield a breakthrough.
A second round is due to begin tomorrow in the Emirati capital - expected to focus on the crucial issue of territory.
Russia has demanded that Kyiv withdraw from the Donestk region and has repeatedly said it is ready to seize the rest of east Ukraine by force if diplomacy fails.
Kyiv sees this as unacceptable.
