U.S. would consider no-fly zone in Syria if Russia agrees

The United States is prepared to discuss with Russia joint efforts to stabilize war-torn Syria, including no-fly zones, U.S. 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," Tillerson said in a statement ahead of this week's Group of 20 summit in Germany.

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.

Tillerson also said Russia had an obligation to prevent the use of chemical weapons by 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.

U.S. President Donald Trump and Russian President Vladimir Putin are expected to meet on the sidelines of the G20 summit in Hamburg this week, and Tillerson said Syria would be a topic of discussion.

Russia is 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, 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.

U.S.-backed forces have surrounded Islamic State's stronghold in Syria, the city of Raqqa.

Tillerson lauded U.S. and Russia cooperation in establishing de-confliction zones in Syria and said it was evidence "that our two nations are capable of further progress."

Trump came into office in January seeking to improve ties with Russia that had soured during the Obama administration. 

But Trump is under pressure at home to take a hard line with Putin due allegations that Russians meddled in the U.S. election and possible collusion between the Trump campaign and Russia.