US President Donald Trump said he is “not happy” after Russia launched its deadliest wave of attacks on Kyiv in nine months, telling President Vladimir Putin to “STOP!” as he attempts to push Ukraine to agree on a contentious ceasefire proposal.

Vladimir, STOP!” the U.S. president wrote in a social-media post addressing the Russian leader, after the largest attack on Ukraine’s capital this year.

Trump's message to Vladimir Putin came a day after the American president said he believed that "Russia is ready" for a peace deal with Ukraine.