On 20 June 2025, the Organisation for the Prohibition of Chemical Weapons (OPCW) has transmitted to Ukraine a report on a third Technical Assistance Visit (TAV) following an alleged incident of use of toxic chemicals as a weapon.
Upon Ukraine's request, under subparagraph 38(e) of Article VIII of the Chemical Weapons Convention (CWC) , the OPCW Technical Secretariat deployed to Ukraine twice in relation to an incident of alleged chemical weapons use along the confrontation lines between opposing forces in the Dnipropetrovsk region.
During their two missions, the experts from the Technical Secretariat (TAV team) collected documentation and digital files, testimonies from first-hand witnesses, and received seven environmental samples collected by Ukraine: two grenade shells (one of them collected with parts of a fuse system), two soil samples, two vegetation samples, and remnants of one first-person view drone, all collected from a location adjacent to a dugout at an observation post, along the confrontation lines with the opposing troops.
Upon return to the OPCW's Headquarters, the samples were sent to two OPCW designated laboratories selected by the OPCW Director-General, Ambassador Fernando Arias, for independent analysis. This activity was carried out following OPCW procedures and in the presence of observers from the Permanent Representation of Ukraine to the OPCW.
Taken together, the documentation and evidence handed over by Ukraine to the TAV experts during the visits, the content of the digital files provided, as well as the information collected and the narrative described by first-hand witnesses, enabled the TAV experts to corroborate that, as reported by Ukraine to the OPCW TAV team, the chain of custody of the seven samples collected from locations adjacent to dugouts located along the confrontation lines with the opposing troops, had been maintained.
The analyses by the OPCW designated laboratories, conducted separately and independently from one another, confirm that all the grenades collected from dugouts at the observation post and at the resting position contained the riot control agent CS, CS-related compounds and/or their degradation products; the soil and vegetation collected from the locations where the grenades were found also contained CS, its precursors and/or its degradation products; and the soil sample collected approximately 15 metres away from one of the grenades in the incident location as well as the solvent wipe sample from the frame of remnants of the collected FPV drone also contained CS at very low levels.
This is the third report released by the Technical Secretariat confirming the presence of CS, a riot control agent, in the Dnipropetrovsk region, along the confronting line. The first report was released in November 2024, and the second one was released in February 2025.
Under the CWC, the use of riot control agents as a method of warfare is prohibited.
Upon receipt of the TAV report on 20 June 2025, the Permanent Representation of Ukraine to the OPCW immediately requested the same day that the Technical Secretariat declassify and share the full report with all States Parties to the CWC and publish it on the OPCW public website.
"The repeated discovery of riot-control agent grenades near active conflict zones in the Dnipropetrovsk region is deeply concerning," said Director-General Arias. "This marks the third such confirmed incident and highlights the pressing need to reinforce adherence to the Chemical Weapons Convention. More than ever the international community must remain vigilant in defending the long-standing norm against the use of chemical weapons in any context."
Director-General Arias reaffirmed the Technical Secretariat's readiness to continue providing its assistance to CWC States Parties through its independent expertise. He also thanked the OPCW designated laboratories that supported the technical assistance request for their independent work and swift analysis.
Background
The OPCW Technical Secretariat has been monitoring the situation on the territory of Ukraine since the start of the war in February 2022 in relation to allegations of use of toxic chemicals as weapons.
In November 2024, the Technical Secretariat released its first report on an OPCW TAV to Ukraine, which confirmed the presence of CS in the samples collected during the TAV. The TAV was conducted in relation to an incident that reportedly took place along the confrontation lines in Dnipropetrovsk region on 20 September 2024.
In February 2025, the Technical Secretariat released its second report on an OPCW TAV to Ukraine, which confirmed the presence of CS in the samples collected during the TAV. The TAV was conducted in relation to incidents that reportedly took place along the confrontation lines in Dnipropetrovsk region in October 2024.
Both the Russian Federation and Ukraine have accused one another and reported a number of allegations of use of chemical weapons to the Organisation.
A compendium of all official correspondence by States Parties on such allegations and accusations has been made available on the OPCW public website and is regularly updated.
Under the Convention, States Parties have the obligation to declare all toxic chemical agents they hold for riot control purposes. Furthermore, the Convention explicitly prohibits the use of riot control agents as a weapon of war on the battlefield. If used as a method of warfare, these agents are considered chemical weapons and, hence, are prohibited under Article I paragraph 5 of the Convention.
Article II, paragraph 7 of the Chemical Weapons Convention, provides that a Riot Control Agent is defined as any chemical not listed in a Schedule, which can produce rapidly, in humans, sensory irritation or disabling effects which disappear within a short time following termination of exposure.
Article VIII, paragraph 38(e) of the Chemical Weapons Convention states that the Technical Secretariat shall provide technical assistance and technical evaluation to States Parties in the implementation of the provisions of the Convention, including the evaluation of scheduled and unscheduled chemicals.
The OPCW has been providing assistance to Ukraine under Article X of the Chemical Weapons Convention, enhancing the country's capacity to detect and respond to chemical threats. This support has included multiple technical assistance visits, delivery of advanced detection equipment, and specialised training for Ukrainian first responders and experts. These activities have been supported by voluntary contributions, to date totalling EUR 6,157,992, from 17 States Parties to the CWC. Thus far, a total of EUR 2,983,361 of these contributions has been spent for activities related to Ukraine.
OPCW experts and designated laboratories are a lynchpin of the Organisation's verification regime and its capacity to investigate allegations of chemical weapons use. Upon request from the Director-General, OPCW designated laboratories perform off-site analysis of chemical samples collected during OPCW deployments. They offer the necessary assurance to States Parties that chemical analyses needed to determine or to clarify issues related to such allegations are carried out competently, impartially, and with unambiguous results.
As the implementing body for the Chemical Weapons Convention, the OPCW, with its 193 Member States, oversees the global endeavour to permanently eliminate chemical weapons. Since the Convention's entry into force in 1997, it is the most successful disarmament treaty eliminating an entire class of weapons of mass destruction.
In 2023, the OPCW verified that all chemical weapons stockpiles declared by the 193 States Parties to the Chemical Weapons Convention since 1997 - totalling 72,304 metric tonnes of chemical agents - have been irreversibly destroyed under the OPCW's strict verification regime.
For its extensive efforts in eliminating chemical weapons, the OPCW received the 2013 Nobel Peace Prize.
