Russia is using toxic chemical weapons, wrecking a ban it helped create

The 1993 Chemical Weapons Convention was one of the most important disarmament treaties to follow the Cold War, one of several that reduced tensions and built norms discouraging some of war’s many horrors. With the support of the Soviet Union and later Russia, it eliminated an entire class of weapons using chemical agents. But in Ukraine, Russia is now using chemical weapons it once agreed to outlaw.