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 glide bombs and missiles have struck a Ukrainian prison and a medical facility, killing at least 22 people

The attack, which came just hours after President Trump gave the Kremlin a new deadline to work toward ending the war, was part of a wave across the country, the authorities said.