In the past three days, the Syrian government made an unprecedented acknowledgment that it possesses a chemical weapons program, and that it will place them under the supervision of United Nations (UN) inspectors. As Syrian foreign minister Walid Moallem stated on Monday: “We are ready to reveal the locations of the chemical weapon sites and to stop producing chemical weapons and make these sites available for inspection by representatives of Russia, other countries and the United Nations.” This remarkable shift occurred after President Obama declared on August 31 that he would conduct limited strikes against Syrian regime targets, after receiving congressional authorization. Subsequently, the Obama administration has repeatedly claimed that it was only the credible threat of force that compelled Syrian President Bashar al-Assad to reportedly agree to the initiative that had been discussed between American and Russian diplomats for months.

On Tuesday, Secretary of State John Kerry claimed:

But for the threat of the use of force, they have never even admitted they have [sic]. Now, they’re not only admitting they have them, but they say they’re prepared to try to live up to some international standards. That is only happening because we have shown them that we are prepared to do what is necessary to hold them accountable.

Yesterday, White House spokesperson Jay Carney was more definitive:

It was the credible threat of U.S. military action that led to the opening of this diplomatic avenue. There is no other explanation behind this rather remarkable change of position by the Syrians and no other explanation behind the decision of the Russians to seek a diplomatic resolution to the problem of Syria’s chemical weapons stockpile…I think there’s no question based on what the Russians have said, and the Syrians said, and what we know that the credible threat of U.S. military action precipitated this. And I’m not sure what other source you ascribe it to or it could possibly be. I don’t think there any doubt that this credible threat of force has produced this change in dynamic.

Also yesterday, State Department spokesperson Jen Psaki was repeatedly questioned by Matt Lee of the Associated Press:

QUESTION: -- The crux of this whole argument – both the White House and you have made this – that it was the credible threat of U.S. force that created this diplomatic opportunity…How do you know that? Is that just your assumption, or have the Russians and the Syrians somehow communicated to you that this is in fact the case? And the reason I ask this is because it is rare…for someone from any podium, this one or the White House or – to ascribe motivation to foreign governments. The answer is always, “Well, I can’t read their minds. I have no idea what they’re doing – they’re doing what they’re doing.” How do you know that force, the threat of force, was the main factor here, or the only factor?

MS. PSAKI: What I can say is that there’s no question that the interest and willingness to engage on this particular issue that the Secretary had spoken about Foreign – with Foreign Minister Lavrov about on several occasions in the past increased as the threat of force, as discussion of that, as the decision by the President was made public and became more likely.

QUESTION: Okay. But it’s an assumption. It’s not like Lavrov said, “Ooh, the threat of force is what got us to – got me to move.”

MS. PSAKI: Well, those two lines are certainly factual, so I would of course allow you to make your own decision.

It is too early to know if a negotiated deal to place Syria’s chemical weapons under international control will succeed, and there will not be a clear answer for some time given the need to pass a UN Security Council resolution, as well as ensuring operational and technical hurdles. However, for foreign policy watchers and international relations scholars, it matters whether Syria can be considered a successful case of coercive diplomacy. If the lesson that one concludes from the past week is that threatening force works, then presumably officials and policymakers in Washington will call upon this strategy in the future, perhaps with Iran over its nuclear program. The question that Matt Lee asked— “How do you know that?”—is one that scholars have difficulty answering with any certainty. How do you prove causation in coercive diplomacy, especially when the coercer wants to claim credit to demonstrate resolve to future target states, and the coercee wants to deny it was compelled to do something that it would not have otherwise done?

Claiming with total certainty—as the Obama administration has done—that it was only the threat of force that led Assad to change his position is dangerous since any judgment is subjective and would be made with incomplete information. Moreover, it diminishes any role that positive inducements could have played in conjunction with the military threats. Russia could have warned Syria that it had to acknowledge its chemical weapons program and place it under international inspection, or Russia would withdraw its essential economic and military support. Alternatively, Russian officials could have told Assad that if he complied with this demand Russia would increase its support, thus helping to assure that he remained in power.

Furthermore, Assad could have believed that the reported three-day cruise missile barrages would have been vastly more expansive and lethal than was assumed in Washington policy circles, and would have been just the first steps of a military campaign to ensure regime change. When a greater-than-threatened use of force is used to achieve the desired political objective, coercive diplomacy has not worked. As international relations scholar Robert Art wrote: “Wherever one draws the line between limited and full-scale use, if the coercer has to cross that line to achieve its objectives, then, by definition, coercive diplomacy has failed.”

As two major studies of how the U.S. threatens force demonstrated, coercive diplomacy only works roughly 30 percent of the time. They also show that coercion (making an adversary change their behavior) is much more difficult to achieve—especially over extended periods of time—than deterrence (attempting to maintain the status quo by discouraging an adversary from initiating a specific action). Finally, Art also provided an important caveat that policymakers should bear in mind if they think coercive diplomacy should be applied to future adversaries, say Iran:

Next to outright war, however, coercive diplomacy represents the most dangerous way to use a state’s military power because, if coercive diplomacy fails, the state that tried it then faces two stark choices: back down or wage war. The first risks loss of face and future bargaining power; the second, loss of life and military defeat.