The United States is considering a possible deal whereby Russia and Iran would stop Syria's regime dropping barrel bombs on civilians in return for concessions from Washington, US Secretary of State John Kerry said.
Having accepted that President Bashar al-Assad will stay in power for a "transitional period", the US is trying to persuade Russia and Iran to curb the worst excesses of their ally.
Assad's forces have killed at least 11,000 civilians by using helicopters to drop barrels packed with explosives, shrapnel and flammable liquid. Kerry said that forcing the regime to stop using these weapons - which breach international humanitarian law - was a priority. He told the BBC that he had raised this issue with Sergei Lavrov, the Russian Foreign Minister, and with Iranian officials.
"They are both in a position, in exchange perhaps for something that we might do, they might decide to keep Assad from dropping barrel bombs."
Kerry also raised the possibility of localised ceasefires in Syria - something that has already happened in various areas of the country. "We have to save Syria. The world has to save Syria. This has dramatic implications for the entire region globally."