Russian President Vladimir Putin spurned a challenge to meet face-to-face with Ukrainian President Volodymyr Zelenskyy in Turkey on Thursday, instead sending a second-tier delegation to planned peace talks, while Zelenskyy said his defense minister would head up Kyiv's team.

They will be the first direct talks between the sides since March 2022, but hopes of a major breakthrough were further dented by U.S. President Donald Trump, who said there would be no movement without a meeting between himself and Putin.

U.S. Secretary of State Marco Rubio later echoed that view, telling reporters in the Turkish resort of Antalya that Washington "didn't have high expectations" for the Ukraine talks in Istanbul.