In central Asia and Africa in the 19th century, governments would often organize “punitive expeditions” to punish governments or non-governmental actors that had offended them or violated international laws or norms. The record is not particularly illustrious.
Commentor David Allen raises the possibility that the United States would engage in the equivalent of a punitive expedition rather than try to materially affect the course of the war or overthrow the Assad regime. I think he is correct that this is what the U.S. will do. In fact, that is how I read press stories like this one. We will launch cruise missiles, back-to-the-Nineties style.
But there are still problems. First, what will the missiles target? Given that Damascus now knows an attack is coming, they presumably have dispersed and hardened their chemical weapons depositories and command systems. Now, if Assad is a good player of 11th-dimensional chess, he won’t do that. Rather, he will let the United States and its allies extract their pound of flesh by destroying his weapons and allowing him to get on with fighting his war the old-fashioned way, free of the fear of American intervention. Problem is, Assad shows few signs of being an astute chess player, let alone in eleven dimensions.
If the missiles target other aspects of the Syrian command system, the same problem applies. Similarly, cratering airfields is emotionally satisfying, but easy to fix, and doesn’t much slow helicopters anyway.
Second, what will be our counter-counter to the inevitable counter-moves? Will Iran and Russia increase their assistance? They might. Will Syria start stepping up artillery barrages? (Artillery is an extremely effective weapon of depopulation.) Can we be sure that the attacks will be targeted so as to not aid anti-American opposition forces? If we are playing 11-dimensional chess, it might be worth it to strengthen the regime while appearing to attack it ... but nobody has ever been good at that game. (I welcome historians to prove that last clause wrong!)
At the end of the day, I suspect we will use cruise missiles against the chemical weapons capacity as best as we can (which is not very well) and hope that provides sufficient disincentive to keep the Assad government from using them again. (Presumably Damascus would fear that we would be forced to attack the regime directly the next time around, cost be damned.) That is probably what I would do if I were President, even without unified international support. After all, it holds out the possibility that by weird quantum kabuki further chemical attacks might be prevented, and that is a taboo worth establishing.
But a missile attack on the chemical weapons systems is by no means assured of success and it is by no means an obvious course of action. The debate is open.