Let’s get this out of the way first: President Donald Trump didn’t actually say the words “red line.” In fact, he, his National Security Advisor, and his Secretary of State say so many different things that it can be hard to tell whether there are red lines, let alone where they are.

In August 2012, President Barack Obama explicitly laid down a red line to President Bashar al-Assad of Syria: Move chemical weapons around, and we will strike. A few days later, Assad brutally killed over a thousand people in Ghouta with sarin. Congress and allied nations were reluctant to back a military strike in response. But then Russian Foreign Minister Sergei Lavrov offered another response: Syria would join the Chemical Weapons Convention and give up its stock of chemical weapons and the means to make more.

It might seem that disarming Syria of chemical weapons was an appropriate punishment for their use after an ulitmatum was issued. No longer would they have that set of tactics available. The benefit to the rest of the world is obvious – ending that form of brutality and the threat to other nations in the region. Missile strikes could never have done that.

Trump withdrew from the Joint Comprehensive Plan of Action (JCPOA), which limited Iran’s nuclear program to a greater degree than for other signatories of the Nuclear Nonproliferation Treaty. He then imposed additional economic sanctions on Iran, in contravention of what had been agreed. A number of small provocations then ensued, and Trump and his advisors threatened war, only to rescind the threat at the last minute. This action is being compared broadly to the 2012 actions.

Let’s look at the comparison in more detail.

In August 2012, a civil war was in progress in Syria. The United States was involved, but not as a primary actor.

The recent provocations against ships have been relatively small and ineffective. They were likely carried out by Iran or its proxies, but the evidence made public is less than conclusive. A military attack on Iran would be disproportionate.

Obama’s clearly stated objective was to end Assad’s use of chemical weapons against civilians. A military strike would have limited that capability, but would not have ended it.

Secretary of State Mike Pompeo has presented to Iran a list of 12 demands to Iran that no country could accede to, short of defeat in war. Trump has said that all he wants is for Iran not to build nuclear weapons. It is not clear how a limited strike against Iran would further these demands.

When presented with an alternative to military action that would be more effective in reaching his objective, Obama changed direction.

Trump and his aides have presented four or five explanations for his change of direction. We have no way of knowing the truth.

Syria’s chemical weapons stockpile was mostly removed and the ability to make more curtailed. Assad seems to have retained a small amount of sarin, which he has used in attacks since the disarmament. He has also used chlorine, a dual-use chemical that is regulated differently. Equivalent attacks with sarin would have been much more deadly.

It’s too soon to judge the effect of Trump’s action.

Obama was excoriated for not holding to his red line. Much of the US foreign policy establishment puts great stock in military action and was disappointed that Obama chose chemical weapons disarmament over missile strikes. The commentary on Trump’s action has been much more moderate, but there is some warning about threats and confidence. For example,

.⁦@realDonaldTrump⁩ right not to strike Iran;costs would have exceeded benefits. But restraint comes at a price, as his will to use force is suspect, likely inviting future challenges. This is what happens when you adopt a policy w/o thinking it thru https://t.co/uPosIHEJI5

— Richard N. Haass (@RichardHaass) June 23, 2019

Many reasons are possible for the more moderate response. Perhaps we have become accustomed to Trump’s bluster without followthrough. Perhaps the situations are different enough that the response is justified. And perhaps Obama, by taking a more effective and peaceful route, broke the attraction of violence.

Cross-posted at Nuclear Diner.