Ukraine’s president is demanding tough new sanctions on Russia following the largest aerial assault on his capital in weeks — one in which British and EU offices were struck, infuriating leaders across Western Europe.

At least 17 people, including three children, were killed in the Thursday morning drone and missile assault, the first significant attack on Kyiv in weeks as American-led peace efforts remain stalled, the Associated Press reported.

A total of 598 drones and 31 missiles were aimed at targets across Ukraine in one of the largest attacks since the February 2022 invasion began, with Ukrainian forces intercepting all but 41 weapons, according to CBS News.

It comes less than two weeks after President Trump’s high-profile summit in Alaska in which the American leader tried to nudge the Russian and Ukrainian leaders toward peace talks. 

“A horrific and deliberate killing of civilians,” President Volodymyr  Zelensky said on X, where he announced a preliminary death toll. Another 38 people are reported to have been wounded.

“The Russians are not choosing to end the war, only new strikes,” Mr. Zelensky wrote. “It is crucial now that the world responds firmly. Russia must stop this war it started and continues. For the spurning of ceasefire and for the constant Russian attempts to weasel out of negotiations, new strong sanctions are needed.”

Mr. Zelensky said that dozens of homes, offices, and other buildings were among those hit in the assault, including “where the European Union Delegation to Ukraine is located.”

“Horrified by yet another night of deadly Russian missile attacks on Ukraine,” the European Council president, Antonio Costa, said on X. “The EU will not be intimidated.”

The European Commission president, Ursula Von der Leyen posted a similarly defiant response to the assault on X following conversations with Mr. Zelensky and President Trump.

 “We must secure a just and lasting peace for Ukraine with firm and credible security guarantees that will turn the country into a steel porcupine,” she wrote. “Europe will fully play its part.”

Also struck in the attack was the office building of the British Council, according to a social media post by Prime Minister Keir Starmer, who echoed Mr. Zelensky’s sentiment.

“Putin is killing children and civilians, and sabotaging hopes of peace,” he said in the post on X. “This bloodshed must end.”

British media reported that the Russian ambassador at London has been summoned to the Foreign Office to hear a formal protest.

The attack could strengthen the resolve of Western European leaders who have been meeting to discuss what kind of security guarantees — up to and including boots on the ground — they could offer Ukraine in the event of a peace settlement.

The relentless assault began at about 9:30 p.m. prompting emergency shelter warnings nationwide. A top adviser to Mr. Zelensky, Andriy Yermak, described the horror while it was still under way.

“Rescuers are working everywhere, but drones continue to fly overhead. Isn’t that enough to understand who Putin is and what his words are worth?” he said. “We extinguish [flames as] buried people are screaming from under the rubble and Shahed [drones fly] over your head.”