"Today in Kazakhstan, Putin once again promoted his missiles — his readiness to kill and destroy. To the thousands of missiles that have already struck Ukraine, Putin clearly wants to add thousands more," Ukrainian President Volodymyr Zelenskyy said Thursday on X, formerly Twitter.
He also slammed a "despicable escalation" by Russia as he accused its military of firing cluster munitions on Ukraine's energy grid in a massive overnight attack.
More than a million Ukrainians were without power in freezing cold temperatures after Russia launched a barrage of almost 200 cruise missiles and drones at energy sites across the war-torn country.
Ukraine is bracing for what could be its toughest winter of the almost three-year war as Moscow steps up its aerial bombardment and its troops advance on the front lines in the east.
Tensions have ratcheted up dramatically over the last few weeks, with Moscow pledging retaliation for Ukraine firing U.S.-supplied missiles on its territory.
Both sides are looking to secure the upper hand on the battlefield ahead of Donald Trump's inauguration as president in January.
Zelenskyy accused Moscow of escalating the conflict by using cluster munitions in the overnight attack.
"In several regions, strikes with cluster munitions were recorded, and they targeted civilian infrastructure," he said in a post on Telegram.
"This is a very despicable escalation of Russian terrorist tactics," he added.
He said Ukraine needed more Western air defense systems "now" to protect against the Russian strikes.
"This is especially important in winter, when we have to protect our infrastructure from targeted Russian attacks."
Russia fired 91 missiles and 97 attack drones at Ukraine in the wave of attacks through the early hours of Thursday, Ukraine's air force said.
It said it downed 79 of the missiles and 35 of the drones, with the rest of the drones "lost" from its radar screens or downed by electronic jamming defensive systems.
But at least some of the missiles hit their targets, Ukrainian officials admitted.
"Power facilities in several regions were damaged," the Ukrenergo electricity operator said, adding that it had introduced emergency blackouts across the country.
Authorities in the Lviv and Kyiv regions said critical infrastructure sites had been hit.
The attack, launched as temperatures across the country hit 32 degrees Fahrenheit, knocked out electricity for more than a million subscribers in Ukraine's west, hundreds of kilometres from the front lines.
"As of now, 523,000 subscribers in Lviv region are without electricity," regional head Maksym Kozytskyi said on social media.
The western region, which borders EU and NATO member Poland, has been spared the worst of the fighting of Russia's 33-month invasion but has been targeted in Russian drone and missile attacks sporadically.
Regional officials said at least another 280,000 were cut off in the western Rivne region and another 215,000 in the northwestern Volyn region, which also borders Poland.
At around 12:00 p.m., Ukrenergo said emergency power cuts had been lifted, though scheduled regional outages remained in place.
The northeastern city of Kharkiv and port city of Odesa on the Black Sea were also targeted.
AFP journalists in Kyiv heard blasts ring out over the capital overnight as air defense systems targeted Russian drones and missiles, with locals crowding into the underground metro system for cover.
The energy ministry said it was the 11th massive Russian attack on Ukraine's civilian energy infrastructure this year.
A senior U.N. official, Rosemary DiCarlo, this month warned Russian attacks on Ukraine's energy infrastructure may make this winter the "harshest since the start of the war."
Both Ukraine and Russia have used cluster munitions throughout the conflict, experts say.
The weapons are packed with smaller munitions that explode midair, scattering bomblets over a wide area.
More than 100 countries have banned their use due to their potential for indiscriminate damage and high rate of duds — with many of the smaller munitions not exploding upon impact, effectively becoming land mines that can detonate years later.
Neither Ukraine or Russia has banned their use and more than 1,000 people have been killed or wounded by them in Ukraine since Russia invaded in February 2022, according to the Cluster Munition Coalition said in September.
Zelenskyy's allegation that Russia is now using them to strike on Ukraine's energy facilities comes after Moscow pledged retaliation for Kyiv firing U.S.-supplied ATACMS missiles on Russia.
Russian President Vladimir Putin has pledged a strong response to every use of the missiles by Kyiv.
He fired a nuclear-capable hypersonic ballistic missile at the city of Dnipro in a "combat test" earlier this month after Kyiv hit a military facility in a Russian border region in an ATACMS strike.