U.S. President Donald Trump and Ukrainian leader Volodymyr Zelenskiy, in Rome for the funeral of Pope Francis, met one-on-one in a marble-lined Vatican basilica on Saturday to try to revive faltering efforts to end Russia's war with Ukraine.

The meeting between the two world leaders would have had the late Pope Francis "filled with hope," the last U.S. ambassador to the Vatican said.

The president’s comments came after he said Crimea “will stay with Russia,” a position backed by the mayor of Kyiv, who conceded that his country may have to give up territory.

President Donald Trump is calling for Ukraine and Russia to meet for “very high level talks,” saying they are “very close to a deal” after productive meetings.

U.S. President Donald Trump on Friday said Ukraine has not yet signed a deal on rare earth minerals and he hopes it will be signed immediately. "Ukraine, headed by Volodymyr Zelenskyy, has not signed the final papers on the very important Rare Earths Deal with the United States.