The 2013 Ghouta chemical attack during the Syrian Civil War was the deadliest use of chemical weapons since the Iran-Iraq war. Intelligence agencies of Israel, the UK, the US, France, Turkey, and Germany concluded that the Syrian government of President Bashar al-Assad was most likely responsible for the attacks. Russia by contrast blamed an opposition group.
The fact-checking website Rootclaim's analysis concluded there was a 96% probability the rebel group Liwa al-Islam perpetrated the attack, and Rootclaim offered a 100,000 dollar challenge on this topic.