WASHINGTON — The United States and Russia are nearing an agreement on Syria for how they hope to resolve the Arab country’s civil war once the Islamic State group is defeated, officials said Thursday.

If clinched, the deal could be announced by President Donald Trump and Russian President Vladimir Putin after a meeting in Vietnam on Friday, four U.S. officials said. The United States has been reluctant to hold a formal meeting between the leaders unless they have a substantive agreement to announce.

The potential understanding comes as an array of forces are near a final defeat of IS, the extremist group that once controlled vast stretches of both Iraq and Syria. Fighting the group is no longer top priority, shifting the focus back to Syria’s intractable conflict between President Bashar Assad’s government and rebels — and to concerns that foreign powers such as Iran will now dominate the country’s future.

The U.S.-Russian agreement being discussed would focus on three elements, officials said: “deconfliction” between the U.S. and Russian militaries, reducing violence in the civil war and reinvigorating U.N.-led peace talks. The officials weren’t authorized to discuss the deliberations and requested anonymity.