More than 360,000 people have been killed in Syria since 2011.
The leaders of Russia, Germany, France and Turkey are meeting in Istanbul to discuss ways to end the fighting in Syria, in particular in the last rebel stronghold in Idlib province.
The hope is to extend outwards the fragile ceasefire that is not quite holding in Idlib as well as work on ways to encourage Syrian refugees to return to their country.
On Friday Syria's White Helmets reported more regime shelling of targets in Idlib and claimed that seven civilians were killed.
Russia has turned the war in Syria around by helping its ally Syrian president Bashar al-Assad fight the rebels and they're now nearly all defeated.
Turkey's president Tayyip Erdogan wants to drive out Kurdish fighters from northern Syria who could help Kurdish fighters who are inside Turkey.
Successive Turkish governments have battled with a Kurdish insurgency for decades.
But the United States has been using Syria's Kurdish fighters to defeat so-called ISIS which has further strained relations between the US and Turkey, which are two NATO member states.