The main Syrian opposition group has said it will join peace talks that have opened in Geneva.
The Saudi-backed High Negotiations Committee (HNC) earlier said it would only join if Syrian government forces ended their air strikes and blockades.
UN envoy Staffan de Mistura has already met the Syrian government's delegation in the Swiss city.
More than 250,000 people have died and 11 million have fled their homes in almost five years of war in Syria.
The Syrian civil war has also been the biggest driver behind Europe's migration crisis.
On Saturday, at least 39 migrants, among them children, drowned in the Aegean Sea while trying to cross from Turkey to the Greek island of Lesbos.