US President Donald Trump condemns Russia's overnight attack on Ukraine as "very bad timing", adding "I am not happy".
Ukraine's President Zelensky branded the strikes, which killed at least 10 in Kyiv, as "difficult" and "impudent".
Writing on his Truth Social account at just before 08:30 local time in Washington DC, Trump said the deadly strikes on Kyiv were "not necessary, and very bad timing".
"Vladimir, STOP!" he concluded. "5000 soldiers a week are dying. Let's get the Peace Deal DONE."
The blunt message comes just hours after Trump criticised the Ukrainian president on the same platform.
"He [Zelensky] can have peace or, he can fight for another three years before losing the whole country," Trump wrote on Wednesday, adding that Zelensky was the "man with no cards to play".
Trump's message to Putin is a relatively rare condemnation of the near-daily Russian strikes on Ukraine - and a sign of his frustration.
The US president promised to resolve the Ukraine war on "day one" of his presidency, and the 100th day comes later this month.
As the deadly overnight strikes on Kyiv and elsewhere in Ukraine show, there is no end to the war in sight.
During a cut-short visit to South Africa, Zelensky said "more pressure" must be put on Russia to achieve a ceasefire.
It comes a day after the US president accused Zelensky of harming peace talks by not recognising Russian control of Crimea - read about the territory's significance.