Russia pounded Kyiv with missiles and drones on Thursday in its biggest attack on the Ukrainian capital this year, killing at least 12 people and drawing a rare rebuke from U.S. President Donald Trump who told the Russian president, "Vladimir, STOP!"

Trump told reporters at the White House that his administration was applying "a lot of pressure" on Russia and reiterated his displeasure with the attack.

But he said significant progress had been made in peace negotiations and the Kremlin had made a "pretty big concession" by being open to "stopping the war, stopping taking the whole country," referring to Ukraine.