Rather than debate the hypothetical results if the administration had ordered strikes in 2013, it is more instructive to examine the policy it did execute, which delivered questionable results at significant cost.
Jeffrey Goldberg, writing recently in the Atlantic, noted with surprise that President Barack Obama's former Middle East adviser Phil Gordon believes that the U.S. should have responded militarily to Syrian President Bashar al-Assad crossing the "red line" of using chemical weapons. President Obama, in contrast, told Mr. Goldberg that he is "very proud" of the decision not to strike, and administration officials have argued that the threat of force paved the way for a diplomatic initiative leading to Mr. Assad shipping out much of his chemical weapons stockpile. So was the non-strike a case study in "deterrent credibility," as Sen. Tim Kaine put it, or of "embarrassingly amateurish improvisation," as one critic said?
Judging a policy requires examining both its outcomes and the cost at which they were achieved. The most straightforward objective -- removing Mr. Assad's chemical weapons stockpile -- succeeded only in part, according to a July 23, 2015, report by The Wall Street Journal. The Syrian regime controlled weapons inspectors' security and movements, and it used that leverage to hinder their work.
Before his decision not to strike, Mr. Obama expressed worry that if chemical weapons were used "and there is no action, then we're sending a signal that that international norm doesn't mean much." Rather than strengthen the international norm against the use of chemical weapons, however, the U.S.-Russian initiative in Syria appears to have had the opposite effect. U.S. officials accused the Assad regime of continuing to use chemical weapons in 2015, well after the inspectors' work was declared complete; yet the violation brought no meaningful response from the U.S. or others. The Islamic State subsequently used chemical weapons as well, according to the Organization for the Prohibition of Chemical Weapons -- prompting U.S. airstrikes on related facilities near Mosul with little debate or fanfare.
The decision not to strike did not stem the Assad regime's killing of civilians, nor did it usher in a period of broader U.S.-Russian cooperation on Syria; to the contrary, the number of civilians killed or displaced rapidly escalated, largely because of Russia's decision to engage militarily in Syria last fall -- an intervention that took the U.S. by surprise and enhanced the lethality of Mr. Assad's attacks on his own populace by lending effective air cover to regime forces and their allies, increasing the tempo of air strikes, and more generally giving the regime time and space to rally its forces.
These results came at a cost. The outcome cited most often is damage to U.S. credibility, which Secretary Kerry had warned was at stake. This cost -- which President Obama seems to dismiss out of hand in the Goldberg interview -- has been invoked heavily by U.S. allies not only in the Middle East but also in Europe, Asia, and elsewhere as they weigh commitments that Washington has made to them. Among allies who were gearing up to support the strikes before they were called off, such as the French, the damage was surely greater still.
Some have argued that the decision not to strike resulted in a badly needed lifeline for the Assad regime, by sparing it from not only strikes on its chemical weapons facilities but any intervention whatsoever, given the presence of inspectors and the Obama administration's need to remain on good terms with Russia, which backs Assad. Indeed, that the U.S. blinked at the moment it was expected to act may have been a factor in Russian President Vladimir Putin's decision to intervene in Syria himself.
Obama administration officials would probably argue a different counterfactual: that intervention in Syria would not have been effective, or could have been a "slippery slope" leading to prolonged military involvement. Some might concede that setting the red line in the first place -- which the president appears to have done without consulting his advisers -- was unwise but that backing away from it was the best of bad choices.
What would have been, of course, is unknowable. Rather than debate a hypothetical action in which the U.S. did not engage, it is more instructive to examine the policy it did execute, which delivered questionable results at significant cost.
Michael Singh is the Lane-Swig Senior Fellow and managing director of The Washington Institute. This article originally appeared on the Wall Street Journal blog "Think Tank."