Staffan de Mistura is building on the fragile ceasefire to lay the groundwork for negotiations in Geneva soon.
A partial truce, drawn up by the United States and Russia, is now into its second week and has slowed the pace of the war.
The ceasefire does not include ISIL and al-Nusra Front fighters.
At least 135 people have been killed since the ceasefire started but it has enabled many civilians to receive badly needed aid.
The Syrian opposition says it is dissatisfied with the implementation of the truce agreement and has yet to say whether it will attend the new talks.
Saudi Arabia has reiterated its position on Bashar al-Assad, saying that the Syrian president has to leave at the beginning of the talks, not the end.
So, will talks take place? And can a ceasefire hold in the future?
Presenter: Sami Zeidan
Vladimir Mikheev, independent analyst with the Troika Report Project.
Julien Barnes-Dacey, Senior Policy Fellow in the Middle East and North Africa Programme for the European Council on Foreign Relations.
Monzer Akbik, member of the Syrian National Coalition.