President Donald Trump said on Monday that Russia and Ukraine "will immediately start negotiations" toward a ceasefire and an end to their 3-year-old war, speaking after he held a call with Russia's President Vladimir Putin.

Volodymyr Zelensky has accused Vladimir Putin of making a “mockery of the entire world” in its delay to respond to calls for a ceasefire after the first stage of a large-scale prisoner swap between Ukraine and Russia.

The Kremlin said Thursday it had not agreed to hold peace talks with Ukraine at the Vatican, denying U.S. media reports that the city-state could soon host negotiations. Russian and Ukrainian officials last week held their first face-to-face talks in more than three years in Istanbul,