Washington DC - President Donald Trump wants a peace deal to end the "senseless killing" in Ukraine, a US official said Thursday after a massive Russian barrage on Kyiv killed at least 21 people.

"President Trump has a humanitarian heart and wants this war settled so the senseless killing ends," the US official told AFP in response to a query on the Russian attack.

"The President and his team have worked very hard to end the war between Russia and Ukraine, and he remains optimistic that we’ll ultimately get a peace deal done."

Kyiv and Moscow both vowed fresh assaults in the four-year war after the huge overnight barrage, which tore open apartment buildings in the Ukrainian capital and sent tens of thousands to shelters.

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Trump said before his return to office last year that he could solve the Ukraine war within 24 hours, but US efforts to broker a ceasefire between Moscow and Kyiv have so far failed.

The US leader has railed against the cost of military aid for Kyiv and famously berated Ukrainian President Volodymyr Zelensky in the Oval Office in February 2025.

In contrast, Trump has taken a largely friendly tone towards Russian President Vladimir Putin, although he has shown growing frustration with Putin's refusal to end the war.

Zelensky on Thursday called on allies to discuss speeding up air-defense aid for his war-torn country at the NATO summit in Ankara next week, which Trump will attend.