"The State Department said Russia had used chloropicrin, a poison gas widely used during World War I, against Ukrainian forces, an act that would violate a global ban signed by Moscow."
"KYIV, Ukraine - 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 on Wednesday 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.
“The use of such chemicals is not an isolated incident and is probably driven by Russian forces’ desire to dislodge Ukrainian forces from fortified positions and achieve tactical gains on the battlefield,” the State Department said. Russia this year has been slowly but steadily pushing through Ukrainian defenses in the east, capturing several towns and villages.
The State Department also said that the United States would impose sanctions on three state entities linked to Russia’s chemical and biological weapons programs and four companies that support them."
Advertisement 
