Both Ukraine and Russia signed and ratified the 1993 Chemical Weapons Convention.
Article I (5) of the Convention states: “Each State Party undertakes not to use riot control agents as a method of warfare.”
Article II (7) defines “Riot Control Agent” as: “Any chemical not listed in a Schedule, which can produce rapidly in humans, sensory irritation or disabling physical effects which disappear within a short time following termination of exposure.”
Videos from Russian and Ukrainian sources released online show that chemical weapons as defined above are being used in the Ukraine war.
Source:
The Gateway Pundit