Phosphorus as a Tactic of War

Russian occupying forces have once again employed incendiary munitions—this time during assaults on the city of Kostyantynivka in the Donetsk region. A video showing characteristic “flares” falling from the sky onto the city’s residential areas was published by aerial reconnaissance specialists of the 28th Separate Mechanized Brigade named after the Knights of the Winter Campaign. According to the brigade’s reports, the Russians utilized a phosphorus charge on this occasion. The occupiers actively employed incendiary munitions—particularly those containing phosphorus—at the onset of the full-scale invasion; however, they have not abandoned this weapon even four years into the war.

White phosphorus is a chemical substance that spontaneously ignites upon contact with air and burns at temperatures exceeding 800 degrees Celsius. Weapons utilizing phosphorus are considered extremely dangerous: fires caused by this substance are exceptionally difficult to extinguish, and any contact between phosphorus and human skin results in severe chemical burns. Furthermore, burning phosphorus emits acrid white smoke, which, notably, can be seen in the video released by the 28th Separate Mechanized Brigade. This smoke also poses a danger to humans and can lead to severe poisoning or burns to the respiratory tract and lungs.

Technically speaking, weapons utilizing white phosphorus do not fall under the definition of chemical weapons; however, international humanitarian law—specifically Protocol III to the UN Convention on Certain Conventional Weapons—imposes restrictions on the use of incendiary weapons. Specifically, its use is prohibited in populated areas and in locations with a concentration of civilians. Another reason for this ban is that incendiary munitions affect a large area and are, by their very nature, indiscriminate weapons.

According to the latest data, approximately 2,000 residents remain in the city of Kostyantynivka—despite the immense danger, daily shelling, the constant threat of enemy UAVs, and the complete absence of conditions conducive to civilian life. Their evacuation had long been extremely difficult, and is now practically impossible. Enemy drones attack any vehicle, including those engaged in evacuation efforts. Several videos circulating online show Russian drones attacking volunteer evacuation vehicles; notably, transport belonging to the “Proliska” humanitarian foundation has come under such attack. The organization has no involvement in military operations and focuses exclusively on humanitarian aid and civilian evacuations.

The incident in Kostyantynivka is far from unique. Attacks involving phosphorus and other incendiary munitions were widespread during the Battle for Bakhmut in 2022 and, particularly, in 2023. During the bombardment of Bakhmut with such weapons, a significant number of civilians remained in the city, much like the situation in Kostyantynivka in 2026. Phosphorus munitions were also employed during combat operations in the vicinity of the settlement of Velyka Novosilka, in the southern part of the Donetsk region. Footage documenting these incidents was released by the Ukrainian military in 2022.

However, the “peak” of this type of weapon’s usage likely occurred during the Battle for Mariupol—specifically during the defense of the Azovstal plant. Russian air forces established air superiority within the very first weeks of the fighting for Mariupol, subsequently launching massive, nearly continuous bombing campaigns against both the city itself and the positions held by the Ukrainian military. Phosphorus munitions were also employed in various districts of Mariupol—an occurrence repeatedly documented on video. The most massive attacks of this nature were directed at the Azovstal plant, which served as the final stronghold for the defenders of Mariupol. The use of phosphorus munitions ignited massive fires and generated toxic smoke.

In June 2025, the Ukrainian unit “K-2” released footage and additional intelligence regarding the destruction of a Russian “Grad” multiple rocket launch system (MLRS), which, according to the Ukrainian military, had been loaded with unidentified chemical munitions. This claim is corroborated by video footage published by the unit, as well as by intercepted Russian radio communications in which soldiers urged their comrades to don gas masks because the “Grad was loaded with chemicals.” Theoretically, these could have been white phosphorus munitions, as the Soviet Union did indeed manufacture such rounds—specifically for “Grad” MLRS systems.

Overall, Russian occupation forces frequently employ various chemical agents during combat operations. This practice was particularly prevalent during the battles for Toretsk in the Donetsk region. Fighters from the “Khizhak” Brigade, speaking with journalist Serhii Okunev, reported that the occupiers had attached canisters containing asphyxiating gases to their drones—likely of the “Cheryomukha” type (chloroacetophenone, or CN). It is tear gas—a potent irritant and lachrymator—used by law enforcement agencies in the mid-20th century to disperse demonstrations. “Cheryomukha” causes severe tearing and burning sensations in the eyes, nose, and throat. Due to its high toxicity, it has been almost universally replaced by safer alternatives in the 21st century.

In 2024, the Organization for the Prohibition of Chemical Weapons (OPCW) published a report regarding the possible use of toxic chemicals as weapons by the Russian military. In accordance with the Chemical Weapons Convention, Ukraine requested that OPCW specialists be deployed to investigate a suspected instance of chemical weapons use near Illinka in the Dnipropetrovsk region. The OPCW Technical Secretariat arrived in Ukraine in connection with the incident.

“During the mission, the Technical Secretariat’s team of experts collected documentation and digital files, gathered eyewitness testimony, and obtained three samples collected by Ukraine: a grenade casing and two soil samples taken from a trench. Upon returning to OPCW headquarters, the samples were sent to two OPCW-designated laboratories—selected by the Director-General—for independent analysis. The analyses, conducted separately and independently of one another by the OPCW-designated laboratories, confirm that the grenade and soil samples collected from the trench contain the riot control agent 2-chlorobenzylidenemalononitrile, known as CS,” the Organization for the Prohibition of Chemical Weapons noted in its report.

The OPCW stated that the organization’s Director-General, Ambassador Fernando Arias, “expressed serious concern regarding the findings.”