U.S. President Donald Trump said on Tuesday that the United States would start imposing tariffs and other measures on Russia "10 days from today" if Moscow showed no progress toward ending its more than three-year-long war in Ukraine.

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.

President Donald Trump’s said yesterday he would move up a 50-day deadline for Russia to agree to a peace deal in Ukraine to 10-12 days.