My point concerns the issue as to why deterrence failed. When it comes to deterrence, one of the essential elements is whether the target nation (Syria in this case) knows a country is sufficiently strong to carry out its threat and whether it is willing to do so. There's little doubt that Syria knew that the U.S. is sufficiently strong to deliver on its threat. The latter element was in doubt, because the threat was not tied to critical American interests. Syria calculated that the U.S. might not be willing to deliver on the threat, because absent critical interests there was nothing to all but require U.S. military action. Rhetoric is far cheaper than concrete interests. Hence, Syria ignored the red line and deterrence failed.