Kyiv | The United States has accused Russia of using chemical weapons, including poison gas, “as a method of warfare” against Ukrainian forces, in violation of a global ban on the use of such weapons.

The State Department said in a statement this week that Russia had used chloropicrin, a “choking agent” widely used during World War I, as well as tear gas, against Ukrainian troops. The use of these gases in warfare is banned under the Chemical Weapons Convention, an arms control treaty ratified by more than 150 countries, including Russia.