Top U.S. and Russian diplomats will meet in Saudi Arabia on Tuesday for talks on resetting the countries' fractured relations and making a tentative start on trying to end the Ukraine war.

Both sides played down the chances that the first high-level meeting between the countries since Moscow invaded Ukraine in 2022 would result in a breakthrough.

Nevertheless, the very fact of the talks has triggered concern in Kyiv and Europe — left reeling by Washington's dramatic diplomatic moves towards the Kremlin.