HAMBURG, Germany — The United States and Russia have reached agreement on a cease-fire in southwest Syria, three U.S. officials said Friday as President Donald Trump held his first meeting with Russian President Vladimir Putin.

The deal marks a new level of involvement for the U.S. in trying to resolve Syria's civil war. Although details about the agreement and how it will be implemented weren't immediately available, the cease-fire is set to take effect Sunday at noon Damascus time, said the officials, who weren't authorized to discuss the cease-fire publicly and spoke on condition of anonymity.

Jordan and Israel also are part of the agreement, one of the officials said. The two U.S. allies both share a border with the southern part of Syria and have been concerned about violence from Syria's civil war spilling over the border.

The deal is separate from "de-escalation zones" that were to be created under a deal brokered by Russia, Turkey and Iran earlier this year. The U.S. was not a part of that deal. Follow-up talks this week in Kazakhstan to finalize a cease-fire in those zones failed to reach agreement.

The U.S. and Russia have been backing opposing sides in Syria's war, with Moscow supporting Syrian President Bashar Assad and Washington supporting rebels who have been fighting Assad. Both the U.S. and Russia oppose the Islamic State group in Syria.