The United States will hold separate talks with Russia and Ukraine in Saudi Arabia to iron out details of a possible limited cease-fire in what could be a crucial step toward a full cessation of hostilities in the war.

Russia and Ukraine both agreed this past week to temporarily halt strikes on energy infrastructure, but how and when to implement that partial truce are questions that have yet to be decided as attacks persist.

The talks — to be held in Riyadh, the Saudi capital, with American representatives mediating — are expected to focus on hammering out those details and on safety for shipping in the Black Sea. Kyiv’s delegation will first meet with U.S. mediators on Sunday, a Ukrainian official said, followed by Moscow-Washington talks on Monday.

The Ukrainian official, speaking on condition of anonymity to discuss a sensitive matter, said Sunday’s talks would begin in the evening, Kyiv time. He added that the Ukrainian delegation might hold additional discussions with U.S. officials on Monday, depending on progress.

Steve Witkoff, whom President Trump has tapped to be his personal envoy to President Vladimir V. Putin of Russia, has said that the ultimate goal of the talks is a 30-day full cease-fire that would allow time for negotiations on a permanent truce.