For its part, the Assad regime has said it might only use chemical weapons in the event of foreign intervention in the armed conflict between the government and domestic opposition forces. In July, the Syrian government publicly acknowledged the existence of its chemical stockpile for the first time.
But as the regime’s hold over the capital city of Damascus becomes even more tenuous, there is a very real risk that Mr. Assad’s commanders will nevertheless resort to the use of artillery shells or bombs armed with chemical agents to repel the rebels’ final assault.
Even if the implied threat of direct foreign military intervention deters Assad from using chemical weapons, there is still the possibility that Syria’s chemical weapons storage sites may come under attack and may come under the control of Syrian rebel groups unfamiliar with safe handling and security of chemical weapons. Several suspected chemical weapons storage and production sites are near the contested cities of Aleppo, Damascus, Hama, and Homs.
Options for preventing any of these deadly scenarios are few – and often flawed.