Shibley Telhami makes a necessary point about U.S. “credibility” in the Near East:

For Arabs in Syria, Egypt, and elsewhere, the problem is not American credibility on the use of force; rather, they have a deep mistrust of U.S. aims [bold mine-DL].

It would be quite strange if anyone in the region concluded that the U.S. was not willing to use force quite often simply because it opted not to attack Syria in this instance. Since 1991, the U.S. has fought three larger wars in predominantly Arab countries, to say nothing of the use of drones in several other countries around the world. So there’s not much doubt that the U.S. will back up its threats with force, but there is profound mistrust about why the U.S. uses force. This mistrust is pervasive, and shapes how people in the region will interpret any U.S. military action in Syria. Telhami continues:

Similarly, most Arabs have opposed U.S. action in Syria in large part because they see every American move as intended to serve suspicious interests. (Indeed, Arab public attitudes toward the U.S. role in Syria have not coincided nicely with the region’s strong anti-Assad mood [bold mine-DL].) Even if the U.S. intervenes in Syria under humanitarian auspices, it will be seen as nefarious.

It is improbable, then, that people who don’t believe America is acting because of CW use will draw any new conclusions on CW norms. This is especially true given that the U.S. is acting without international support and, in the process, preparing to violate the strongest of international norms: not attacking another state without U.N. support, except in cases of self-defense [bold mine-DL].

This last point doesn’t seem to mean very much in the American debate, perhaps because the U.S. has violated this norm often enough over the last 15 years that most people don’t take it seriously or don’t even bother to bring it up in their arguments. Whatever the reason, other nations are likely to view a U.S.-led attack in Syria as the violation of international law that it is, and that is bound to color the way they interpret the claim that the U.S. is enforcing an international norm. Some will conclude that norm-enforcement is a mere pretext, and others will ignore the justification all together and focus on the illegality of the U.S. action. Perversely, many of the states that already adhere to the norm of not using chemical weapons will view the U.S. action as illegitimate, and the pariah states that don’t care about international norms will take the attack as a warning that they will need to acquire a deterrent to stop the U.S. from attacking them. As usual, the message that Washington thinks it is sending to the world is not the one that will be received, because many nations around the world don’t trust our motives and they react to U.S. military action in ways that Washington doesn’t want and doesn’t expect them to react.