A Ukrainian battalion said Monday that Russia has used chemical weapons against Ukraine's military and citizens, causing victims to develop respiratory failure and other illnesses.
NATO has warned that the use of chemical weapons could prompt further action from the West.
Late last month, NATO Secretary-General Jens Stoltenberg said that using chemical weapons is a "blatant violation of international law with far-reaching consequences.".
"The #Azov Batallion informs Russia has used an unknown chemical substance against defenders of #Mariupoland civilians.
@POTUS @NATO you announced a strong reaction should Russia use chemical weapons.
The #Azov Batallion informs Russia has used an unknown chemical substance against defenders of #Mariupol and civilians.
White phosphorous is not considered a chemical weapon under the U.N. Chemical Weapons Convention, but its use is tightly regulated under international law. »