Chlorine is not listed on the list of prohibited items by itself freestanding under the Chemical Weapons Convention. But chlorine, when used and mixed in a way that is used as a chemical weapon in the conduct of war, is against the chemical weapons treaty. And I have seen evidence, I don’t know how verified it is – it’s not verified yet – it’s hasn’t been confirmed, but I’ve seen the raw data that suggests there may have been, as France has suggested, a number of instances in which chlorine has been used in the conduct of war. And if it has, and if it could be proven, then that would be against the agreements of the chemical weapons treaty and against the weapons convention that Syria has signed up to.Kerry was then questioned by a reporter about the possible responses if the evidence eventually proves that chemical weapons were indeed used again:
QUESTION: Thank you. Secretary Kerry, to follow up on your last point, if it is proven that chlorine was used as a chemical in war, which is prohibited, what will the Syrian Government face? What steps can be taken?
SECRETARY KERRY: ...With respect to the CW and what the consequences are, it has been made clear by President Obama and others that use would result in consequences. We’re not going to pin ourselves down to a precise time, date, manner of action, but there will be consequences if it were to be proven, including, I might say, things that are way beyond our control and have nothing to do with us. But the International Criminal Court and others are free to hold him accountable. And as you know, we have a resolution that will be in front of the United Nations with respect to culpability for crimes against humanity, atrocities in the course of this conflict. So one way or the other, there will be accountability.In an interview on September 10, 2013, the secretary said that proof of Syria's use of chemical weapons was the "straw that broke the camel’s back" that prompted President Obama to order military strikes against Syria:
That’s when the President decided that that was straw that broke the camel’s back so to speak with respect to his usage. And the President decided that it needed a response from the world because chemical weapons were suddenly being used as a tactical weapon in a civil war, and any use of chemical weapons is unacceptable.
That’s why we’re here where we are today. There’s a moral imperative to this, there’s a strategic imperative to this, there’s a practical military imperative in terms of sending him a message that his infrastructure, militarily, and his capacity to wage war could be affected if he continues to use these prohibited, outlawed, and outrageous weapons.Two days later at an appearance with Russian Foreign Ministry Sergey Lavrov in Geneva, Kerry said that the president maintained that "force might be necessary" "should diplomacy fail[.]" After the Russian-brokered deal with Syria headed off military strikes, Kerry said "Ensuring that a dictator's wanton use of chemical weapons never again comes to pass, we believe is worth pursuing and achieving."
Kerry did not mention a renewal of the strike threat when questioned this Thursday about the consequences to Syria if use of chemical weapons is proven again.
Note: A version of this post first appeared at The Weekly Standard.