Russia's foreign minister has defended his country's airstrikes in Syria.
Sergey Lavrov says he and the US-led coalition "see eye-to-eye" on the fight against terrorism.
Concerns have been raised over who the Russians are actually targeting, and Mr Lavrov has defended the fact that they are co-operating with the Syrian government.
Sir William Patey, a former British ambassador to Iraq, says that may be the only option in the short term.
"Nobody's saying that Assad shouldn't one day be held to account for war crimes or that he's the sort of person you would want to deal with.
"But if the alternative is another five to 10 years of continual civil war and the other 8 million Syrians being displaced, you have to ask yourself, which is the least bad alternative."