The Russian president had been challenged by Ukraine's Volodymyr Zelensky to meet in person at the talks on Thursday.

After Mr. Trump expressed frustration with Russia’s refusal to stop the war, Mr. Putin ordered a three-day cease-fire to begin on May 8, in order to mark the May 9 celebration of the Soviet Union’s victory over Nazi Germany in World War II. Mr. Zelensky described that pledge as a “ manipulation .”