A United Nation plan for Syria is a milestone in the efforts to end the conflict in war hit country, said US Secretary of State John Kerry.
Kerry said the plan gave Syrians a real choice between war and peace.
However, disagreements remain over President Assad and the unanimously agreed Security Council resolution makes no mention of his future role.
Western countries have called for his departure, but Russia and China say he should not be required to leave power as a precondition for peace talks.
