Moreover, the norm against using chemical weapons is not the only international standard at stake. There is also international law prohibiting deliberately and indiscriminately killing civilians, which the Syrian government has flouted on a much larger scale. Against the 1,429 people whom Kerry said were killed by the chemical attack outside Damascus are the tens of thousands of civilians whom Syrian troops and militia have killed in two-and-a-half years of war. Armed opposition groups have also committed their share of indiscriminate shelling and serious abuses against suspected government supporters.
Upholding the norm that civilians should never be gassed is important. So is upholding the law against this broader killing of civilians—which Obama previously described as “a core national security interest.” As the United States prepares to lead a military attack in Syria, the campaign will be measured by its consequences. Will it enhance protection for all Syrian civilians, regardless of how they are attacked? Or does the United States have other plans for doing that? Neither Obama nor Kerry has said.