U.S. Secretary of State Rex Tillerson said on Wednesday that Washington is open to enforcing no-fly zones in Syria in coordination with Moscow.
Joint efforts may also include on-the-ground truce monitors and delivery of humanitarian aid to Syrians.
All of those, likely talking points on Friday at an expected meeting between Donald Trump and Vladimir Putin on the sidelines of the G20 in Germany.
Tillerson spoke to reporters before taking off for the summit.
"I think the important aspect of this is that this is where we've begun an effort to begin to rebuild confidence between ourselves and Russia at the military-to-military level but also at the diplomatic level," said Tillerson.
Tillerson didn't bring up the future of Syrian President Bashar al-Assad, who the U.S. largely blames for six years of civil war, calling for him to step down.
Russia is Assad's major ally.
Tillerson did say Moscow has an obligation to prevent the use of chemical weapons in Syria.
Washington hit a Syrian air base with a missile strike in April after it accused Assad's government of killing dozens in a chemical attack.
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