At least 22 Ukrainians have been killed and another 85 injured in Russian strikes across the country overnight, prompting Ukrainian President Volodymyr Zelensky to call for “very harsh, truly painful” sanctions on Russia.

The Kremlin is yet to officially comment on the new deadline. But Dmitry Medvedev -- the former Russian president and prime minister now serving as the deputy chairman of the country's Security Council -- framed Trump's challenge as a dangerous escalation.

Russian air strikes on southeastern Ukraine killed at least 19 people overnight, officials said on Tuesday, hours after U.S. President Donald Trump said he would shorten a deadline for Russian President Vladimir Putin to make peace.