David Cameron, following US policy, is calling for Bashar al-Assad to take part in an transitional arrangement for a “moderate” regime in Syria.
Cameron has not, so he says, changed his view that Assad must to, or that he should be tried for war crimes. But there has been a policy shift.
At the UN General Assembly Russia and the United States agreed to look for a diplomatic end to the Syrian civil war. How long or whether Assad remains in power is the dividing line between the two powers.