Tierney, in The Atlantic, suggests a "strategic self-interest" for the United States to oppose chemical weapons.
"Powerful countries like the United States cultivate a taboo against using WMD partly because they have a vast advantage in conventional arms," he writes. "... Washington can defeat most enemy states in a few days -- unless the adversary uses WMD to level the playing field."
Rubin rejects that argument, saying the U.S. advantage in weapons of mass destruction precludes any possibility of a level playing field.
And while the alleged previous, smaller-scale use of chemical weapons in the Syrian civil war were not enough to bring about calls for action, he said, "This is such a blatant example, we can't pretend not to see it."