The Organisation for the Prohibition of Chemical Weapons (OPCW) stated Thursday that its inspectors identified CS gas—a riot control agent prohibited in warfare—in seven samples from areas of active conflict in Ukraine. The samples included two grenade casings, two soil and vegetation samples, and fragments from a drone.

The OPCW collected additional material during its investigation, including documents, digital data, and eyewitness testimonies.

Convention Violations Raise Alarm

Under the Chemical Weapons Convention, CS gas is banned as a method of warfare. “The repeated discovery of riot-control agent grenades near active conflict zones in the Dnipropetrovsk region is deeply concerning,” said OPCW Director General Fernando Arias, emphasizing the need to uphold international chemical weapons norms.

Attribution Remains Undetermined

The OPCW did not assign blame to either side. Ukraine claims Russia is deploying tear gas near front lines. Moscow denies this and has in turn accused Ukraine of similar actions.

Previous OPCW confirmations were made in November 2024 and February 2025 following earlier Ukrainian submissions.