The U.S. government’s intelligence report on the use of chemical weapons in Syria does not prove that Bashar al-Assad ordered the horrific attack on August 21. The case is strong in terms of circumstantial evidence that the regime launched the attacks. But after the Iraq WMD fiasco, this may not be enough to persuade many people or governments to take action.
Still, if you believe that preventing the use of chemical weapons by the Syrian government is a national priority for the United States, whether Assad himself ordered the strike does not really matter. As the leader of Syria, Assad is responsible for ensuring that these horrible weapons are not used and that they remain tightly controlled, even in times of conflict. So any skepticism about the intelligence report shouldn't alter the case for taking military action in Syria.
The real question is whether anything—including military strikes—will deter Assad from using (or allowing his forces to use) chemical weapons in the future. The short answer is: no one knows. If we knew how to deter Assad, these horrific attacks would never have happened. President Obama thought that laying out a "red line" would inhibit the regime. It didn't. So it's difficult to have much confidence in our ability in influence Assad.
Nevertheless, the Obama administration must respond forcefully. The United States has a strong national security interest in preventing any use of weapons of mass destruction by anyone, anywhere.
No country would suffer more, strategically, from the widespread proliferation and possible use of such weapons than the US. Having invested generations of political capital to establish the international norm against the use of chemical, biological, and nuclear weapons, America has a responsibility, as well as a self-interest, in enforcing that standard. The alternative would be to accept a world where such weapons are used more frequently.
How this complex equation translates into possible military strikes remains unclear. The strike would have to be designed to send Assad a strong message, inflicting direct pain on him and his control of the state. However, given the administration's stated reluctance to alter the course of the civil war, this would have to be done in a way that did not significantly affect Assad’s control over his military.
The intelligence report released by the government indicates America can identify the units that carried out the attack; those are the ones likely to be targeted. Striking at them could influence other commanders who might be ordered to use chemical weapons or consider using them on their own authority. Holding commanders in the battlefield directly responsible is a tactic that was used in the 2003 gulf war.
No one should underestimate how the shadow of the invasion of Iraq weighs on the minds of those in the administration. But the president cannot allow the past to paralyze him. Yes, America’s word is not worth what it was, a result of President Bush’s actions. Britain's refusal to support a Syria attack is evidence of that. But our strategic interests in preventing chemical weapons use remains.