Making the ban on chemical weapons effective is a different and separate purpose from all of the various conflicting goals being pursued for Syria.  People who want to preserve Alawite power, those who want to overthrow Assad, and those who would like the war to continue without a winner, can all agree that action should be taken in response to Assad’s use of poison gas.

The minimum test for sufficient response to Assad’s use of chemical weapons is that it be strong enough so that it is clear that Assad lost more than he gained by using poison gas in Ghouta.  The object of responding to a violation of the taboo is to demonstrate to future decision-makers – in Syria and elsewhere – that they will lose if they use chemical weapons (CW), because any gain from the use will be over-balanced by international retribution for violating the ban.

It would be better if the response to the use of poison gas were quick.  Better if there were widespread political support for the response – demonstrating that any future use would also produce an international response making that use a loss for the user.  Better if the blow against Assad were strong enough so that no one could doubt that his use of gas was a mistake from his point of view.  But the best should not be the enemy of the good.  It is worth making Assad pay a price explicitly for his use of chemical weapons even if the response is modest, slow, and controversial.

The Russian initiative to “compel” Assad to give up his chemical weapons has significant political effects apart from its impact on CW.  If the net political effects are bad and the effects on future use of CW – by Syria or others – are good, it is necessary to decide which effects are more important – or to find ways to reduce the political harm from pursuing the proposal to eliminate Assad’s CW force.  Here we will only look at the effects on CW of the Russian initiative.

If the outcome is that Syria is prevented by the negotiations from using CW again, and eventually has to turn over a large share of its chemical weapons and the facilities that produced them, it is pretty clear that the Syrian experience will be a useful precedent to deter others from building or using poison gas.  Why spend a lot of money and effort to acquire and maintain CW if after you use it once you will be forced to give up your CW force?

This valuable deterrent effect would be produced even if the inspection provisions forced on Assad are not really adequate, and he continues to hold some covert CW.  But if he gives up most of his force and production capacity, and can’t use whatever he secretly kept without implicitly authorizing international action against himself, he has suffered a loss that is large compared to the benefit he achieved by his use of CW at Grouta.

On the other hand, if the implementation of the Russian-American effort to take his CW away from Assad gets delayed and comes to nothing Assad will have demonstrated that the world cares so little about preventing the use of poison gas that dictators can expect to be able to make good use of it.

Unfortunately there is another benefit Assad is getting from his CW.  By encouraging the Russian-US program to shut down his CW program Assad has bought himself substantial political protection.  Now there is even less chance that the US will act against his regime – at least so long as it is continuing to go forward with giving up the CW force.  In other words, Assad’s CW program is buying a major political shield.  It is not clear what message this “successful” maneuver will have on other countries who have or are thinking of getting a CW force.  It simultaneously suggests that CW can be valuable but that they cannot be used to kill people without paying a price.

The future of the chemical weapons ban can be protected even if the response to Assad’s use doesn’t lead to his downfall.  Of course the lesson would be strongest if it were clear that Assad would have won if he had not used gas and that he was defeated because he did use gas.  But a less clear lesson can be adequate, and is certainly better than a failure to respond.

Support for the ban on chemical weapons is weakened by those who try to use a response to the attack in Ghouta as a way to gain support for other – more controversial — purposes in Syria, or as a way of attacking or defending President Obama’s policy-making.  It is also weakened by those who when faced by a proposal to respond explicitly to Assad’s use of gas begin questioning whether there is much point to making a big thing about killing 1,000 people with gas when Assad has already killed over 100,000 people with ordinary weapons.  It is also weakened by those who argue that there is not much reason to respond to the gas attack if the response doesn’t do something to end such a destructive war.

Fortunately, it is relatively easy to make a minimally sufficient response to Assad’s use of gas.  The reason this is so demonstrates the basic justification for the ban on chemical weapons.  Assad did not gain much by using chemical weapons; therefore it is easy to hit him hard enough so that his losses are greater than his gain.

The world did not agree to ban chemical weapons instead of banning internal war because chemical weapons are worse than war.  Chemical weapons are banned not only because there is a natural revulsion against poison gas, but more because of the understanding that it is feasible to prevent people from using gas and it is not feasible to prevent people from fighting.

People fight, often, because if they don’t they will be killed or conquered.  This makes it hard to deter fighting.  And typically the only way to stop fighting is to put in sufficient outside force to gain control of the territory.  But chemical weapons normally have at most modest advantages compared to high explosive weapons (HE).  CW have more advantage against unprepared civilians than against quality troops with gas masks.  But even against civilians the advantage of CW is limited.  Assad’s father killed more civilians with HE in Homs than Assad killed in Ghouta. Therefore modest action by outside powers can overmatch the incentives to use poison gas.  Therefore a ban on chemical weapons can be made effective.  And it is worthwhile even though it leaves worse evils untouched.

The ban on the use of chemical weapons is not of earthshaking importance.  It is a small step toward making the world a better place.  But it is a step in the right direction, accomplishing something worthwhile, and achieved by great effort over the years.  But even this small step must from time to time be defended or it will be lost.  The chemical weapon ban can be made to work, but if it is not enforced it will lose effectiveness and gradually become a dead letter.

What is needed now, to make the chemical weapon ban effective, is for everyone to recognize their stake in making the ban effective, and therefore to support action against Assad or his CW program, explicitly in response to the gas attack, and strong enough so that he regrets having made that attack.  The more people in the US and other countries demonstrate that they care enough about the chemical weapons ban to make sure that it is implemented in Syria, regardless of other considerations on all sides, the more the ban will be strengthened.