The United States is prepared to discuss with Russia joint military efforts to stabilise war-torn Syria, including no-fly zones, US Secretary of State Rex Tillerson said on Wednesday.
He added the United States wanted to discuss with Russia the use of on-the-ground ceasefire observers and the coordinated delivery of humanitarian aid to Syrians.
"If our two countries work together to establish stability on the ground, it will lay a foundation for progress on the settlement of Syria's political future," Mr Tillerson said in a statement ahead of this week's Group of 20 summit in Germany.
US President Donald Trump and Russian President Vladimir Putin are expected to meet on the sidelines of the summit in Hamburg on Friday, and Mr Tillerson said Syria would be a topic of discussion.
The statement made no mention of Syrian President Bashar al-Assad's future. The United States largely blames Assad for the six years of civil war and has called on him to step down.
Mr Tillerson also said Russia had an obligation to prevent the use of chemical weapons by Mr Assad's government.
Washington hit a Syrian air base with a missile strike in April after accusing the Assad government of killing dozens of civilians in a chemical attack.
Russia is Mr Assad's major ally and Moscow's military support has helped the Syrian government turn the tide in a multi-sided war against Islamic State and Syrian rebels.
As the fight against Islamic State winds down, Mr Tillerson said Russia has a "special responsibility" to ensure Syria's stability.
He said Moscow needs to make sure no faction in Syria "illegitimately re-takes or occupies areas" liberated from Islamic State or other groups.
US-backed forces have surrounded Islamic State's stronghold in Syria, the city of Raqqa.
The offer went beyond the Obama administration's efforts to work with Moscow, suggesting that cooperation in establishing no-fly zones was possible. Mr Tillerson noted that despite differences, the US and Russia are having success in avoiding accidents between American and Russian planes flying over an extremely complex conflict zone. Minor incidents, he said, had been dealt with "quickly and peacefully."
"This cooperation over de-confliction zones process is evidence that our two nations are capable of further progress," Mr Tillerson said. "The United States is prepared to explore the possibility of establishing with Russia joint mechanisms for ensuring stability, including no-fly zones, on the ground ceasefire observers, and coordinated delivery of humanitarian assistance."
Mr Trump came into office in January seeking to improve ties with Russia that had soured during the Obama administration.
But the president has come under pressure at home to take a hard line with Mr Putin due to allegations that Russians meddled in the US election and possible collusion between the Trump campaign and Russia.