Saudi Arabia's crown prince wasn't in the room for the first high-level talks between Russia and the United States over Moscow's war on Ukraine on Tuesday, but Mohammed bin Salman still won the day for hosting the gathering that could be a game-changer in the bloody conflict.

As President Donald Trump presses ahead with his attempt to end the war in Ukraine, he is leaning on an old ally: Saudi Arabia’s powerful Crown Prince Mohammed bin Salman, whose success in mediating an end to the conflict could deepen his already warm ties to the new American president.