There are huge stockpiles of chlorine in water treatment facilities in all of US major cities; worse yet, we openly sell only slightly less potent version of chlorine in supermarkets as bleach. We don't even card the buyers. For all we know one of them may be a Syrian or a Russian.
It is high time to ban this ugly weapon, and go back to healthy living with cholera et al... we just cannot take the chances anymore.
The problem is not chlorine. The problem is Saudi sponsored Sunni wahabbi sect Isis murderers and our inability to properly define the enemy. We have idiots that think it is the government of Syria.