How should America respond to Syria’s use of chemical weapons?

WASHINGTON — On April 22, 1915, chlorine gas, wafted by favorable breezes, drifted from German lines toward enemy positions held by French troops near Ypres, Belgium. This was the first significant use of chemical weapons in a war in which 100,000 tons of chemical agents would be used by both sides to kill almost 30,000 soldiers and injure 500,000.