Russia carried out a major overnight attack on Ukraine that President Volodymyr Zelenskyy said violated a promised halt on strikes against energy infrastructure as the countries prepared for further talks to end Moscow’s four-year full-scale invasion. Zelenskyy, speaking as negotiators were moving toward discussions in Abu Dhabi, said the bombardment included drones and missiles aimed at Ukraine’s power grid, in a wider effort Ukraine describes as seeking to deny civilians electricity, heating and running water during winter.

In his remarks, Zelenskyy tied the timing of the attack to harsh winter weather, saying, “Taking advantage of the coldest days of winter to terrorize people is more important to Russia than diplomacy.” He said temperatures in Kyiv fell to minus 20 degrees Celsius (minus 4 Fahrenheit) overnight and were minus 16 C (minus 3 F) on Tuesday, describing conditions that make energy outages especially consequential.

NATO’s Secretary-General Mark Rutte visited Kyiv during the period of renewed strikes and addressed the Ukrainian parliament, saying that NATO allies “are ready to provide support quickly and consistently” as peace efforts continue. Rutte also said the overnight strikes “raise doubts about Moscow’s intentions on the eve of talks,” calling them “a really bad signal,” and added that he was “clear that the attacks only strengthen Ukrainians’ resolve.”

Ukraine’s officials described the attack as reaching at least five regions, including a push on infrastructure meant to distribute power. Zelenskyy said the strikes targeted the power grid, and Ukrainian officials said the bombardment included 450 long-range drones and 70 missiles. The attack hit substations, transformers, turbines and generators at power plants, Ukraine said, as the country continued efforts to repair damage from repeated assaults.

Ukraine’s power provider DTEK said the overnight attack hit its thermal power plants, describing it as the ninth major assault since October. The cluster also reported that a Kremlin official had said last week Russia agreed to halt strikes on Kyiv for a week until Feb. 1 because of the frigid temperatures, after a personal request from U.S. President Donald Trump to Russian President Vladimir Putin.

Zelenskyy, however, accused Russia of breaking that commitment to pause strikes on Ukraine’s energy assets, saying the weeklong pause was due to come into force last Friday. “We believe this Russian strike clearly violates what the American side discussed, and there must be consequences,” Zelenskyy said. Trump, in turn, said Putin “kept his word” on the temporary pause, telling reporters, “It was, it’s a lot,” and adding that he wanted Putin to extend it and “I want him to end the war.”

In Kyiv, the State Emergency Service said the strikes wounded at least five people and damaged residential buildings, a kindergarten and a gas station across the capital. The Kyiv city mayor Vitali Klitschko said that by early morning, 1,170 apartment buildings in the city were without heating, setting back repair operations that had restored heat to all but 80 apartments before the attack. The report was later corrected to clarify that the figures for buildings lacking services all referred to heating.

The overnight attack also hit Ukraine’s northeastern Kharkiv region, where injuries were reported, and the southern Odesa region. Ukrainian Culture Minister Tetiana Berezhna said the strikes damaged the Hall of Fame at the National Museum of the History of Ukraine in the Second World War in Kyiv, calling the damage “symbolic and cynical at the same time” because she said it involved an aggressor state striking a place of memory about resistance to aggression in the 20th century.

Russian officials provided no immediate response to Zelenskyy’s comments.