Steffan de Mistura spoke to reporters Monday moments before resuming "proximity talks" in Geneva, a month after suspending them in an upsurge in violence in Syria.
The talks come as he said a "fragile" cease-fire has largely held since Feb. 27, and humanitarian aid deliveries have resumed in recent weeks, the Associated Press reported.
Many observers say the peace talks are the best chance in years to end a war moving into its sixth year, leaving at least 250,000 people dead and forcing at least 11 million people to leave their homes - many abroad.