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 Vladimir V. Putin of Russia ordered a three-day unilateral cease-fire in Ukraine next week, the Kremlin said on Monday, soon after President Trump reiterated his frustration with Russia’s refusal to stop the war.

Russian President Vladimir Putin announced Monday a three-day cease-fire in its war with Ukraine is set to take place in May, but Ukrainian officials question its timing and validity.