Without collective international action, peace in Syria could still be a long way off.
Two years ago, up to 1,500 people died when rockets filled with Sarin gas struck the Damascus suburb of Ghouta.
The government denies widespread accusations of being behind the chemical attack.
Survivors are worried they will never get justice.
Al Jazeera’s Zeina Khodr reports from Beirut, where she met witnesses sharing their harrowing stories of the attacks.