Russian President Vladimir Putin on Monday declared a unilateral three-day ceasefire in Ukraine next month, a move met with skepticism by Ukrainian officials who demanded the Kremlin leader immediately accept a longer truce proposal from the United States that he has so far rejected.

President Trump "wants to see a permanent ceasefire first, to stop the killing, stop the bloodshed," press secretary Karoline Leavitt said.

Vladimir Putin calls a three-day ceasefire in May, coinciding with events marking the 80th anniversary of World War Two's end.