But, to settle the bar discussion, any definition of "WMD" includes any chemical weapon designed as a chemical weapon - though there are several thousand people in Bhopal that might argue the point regarding certain industrial chemicals. And, BTW neither mustard or sarin are gases. They are liquids with varying degrees of volatility. They give off vapors, but are not a gas in the true sense of the word, as opposed to something like phosgene or cyanogen chloride.