Join War on the Rocks and gain access to content trusted by policymakers, military leaders, and strategic thinkers worldwide.
The recent news that Russian opposition leader Alexei Navalny’s death was caused by epibatidine — a South American frog toxin — has reignited interest in state use of poisons and toxins in assassinations. Although state use of such compounds has a long history, the erosion of the norms prohibiting assassinations and chemical and biological weapons increases the likelihood of future assassinations using poisons and toxins. As demonstrated in the recent targeting of the Iranian leadership in Operation Eric Fury and in the assassinations of prominent Iranian nuclear scientists, including Mohsen Fakhrizadeh, the assassination norm has collapsed. The norms against chemical and biological weapons use, especially in assassination, have weakened significantly to the point that poisons and toxins likely will become just another tool in the assassin’s toolkit. To date, the anemic international reaction to the use of poisons and toxins in assassinations ensures only continued international acquiescence.
The question then is, why do states use poisons and toxins to eliminate their opponents? Are these compounds in targeted assassination intended to conceal the act itself, or are they intended to signal harm to those who oppose a regime? On Feb. 14, 2026, France, Germany, the Netherlands, Sweden, and the United Kingdom issued a joint statement concluding that the death of Navalny, which occurred on Feb. 16, 2024, during his incarceration, resulted from epibatidine. Analyses conducted in laboratories of these countries confirmed the presence of the substance, which is prohibited under the Chemical Weapons Convention. This extremely toxic compound was most likely synthesized by Russian scientists, thereby implicating the Russian government. Following this announcement, some have suggested that the use of epibatidine in Navalny’s assassination was to “send a message.”
This narrative is notably rooted in the successful Russian assassination of former Russian intelligence officer Alexander Litvinenko in Nov. 2006, as well as the two recent failed Russian assassination attempts: The attempted assassination of former Russian military intelligence officer Sergei Skripal, which also affected his daughter, in Salisbury on March 4, 2018, and the attempted poisoning of Navalny during a flight to Moscow on Aug. 20, 2020. The selection of this agent contributed to the perception of Novichok as a distinctive “Russian signature” deployed by Moscow to signal intent, while reinforcing a narrative placing Russia at the center of state use of poisons and toxins in assassination. Taken together, the use of rare or unusual materials has led some to suggest that messaging was a goal.
However, neither the Litvinenko assassination, the 2018 Skripal attempt, the 2020 Navalny attempt, nor the successful 2024 Navalny assassination supports this interpretation. A closer look suggests that the primary objective was the elimination of an opposition figure without detection or attribution and not theatrical signaling. The historical record of state assassinations further supports this conclusion. It therefore calls for renewed attention to why states favor poisons and toxins in targeted assassination and to the extent to which other states, beyond Russia, may engage in similar covert operations.
Skripal allegedly spied for British intelligence and was arrested and imprisoned in Russia in 2006. Following the 2010 spy swap, Skripal was resettled by British authorities in Salisbury, England, where he lived until he became the victim of a Novichok assassination attempt. On the morning of March 4, 2018, Skripal left his home with his daughter, who had flown in from Moscow the day before to visit him, unaware that the exterior door handle had been contaminated with Novichok in an attempt to kill him. After initially leaving, his daughter, Yulia, briefly reentered the house, also coming into contact with the contaminated handle and becoming exposed to the nerve agent. Both were found unconscious on a bench in central Salisbury. They were rushed into emergency care and survived after intensive medical treatment. Subsequent analyses conducted by the Organisation for the Prohibition of Chemical Weapons laboratories confirmed the use of Novichok. Clearly, Skripal was the sole target, and Yulia was exposed only because the assassins failed to consider her reentry into the house.
Navalny was the most prominent critic of Vladimir Putin. On Aug. 20, 2020, before boarding a flight from Tomsk to Moscow, Navalny’s clothing in his hotel room in Tomsk was contaminated with Novichok. As he became gravely ill soon after takeoff, the aircraft made an emergency landing in Omsk, where he received initial emergency care. He was subsequently medically evacuated to Germany, where he underwent intensive treatment. Laboratory analyses later confirmed Novichok poisoning.
After recovering, Navalny accused Putin of responsibility and implicated Russia’s Federal Security Service. Navalny returned to Moscow in 2021 and was immediately arrested and imprisoned. After multiple convictions, he remained in custody until he was found dead in his prison cell on Feb. 16, 2024. Russian authorities attributed Navalny’s death to “sudden death syndrome,” a broad term for abrupt cardiac arrest. Near the second anniversary of his death, five European countries issued a joint statement accusing Russia of poisoning him with epibatidine. This conclusion was only possible after a concerted effort by Navalny’s family and associates to smuggle samples out of Russia. Had they been prevented from doing so, a definitive cause of death would have remained unknown.
In all three cases, one narrative has been that Russia employed exotic compounds to “send a message” (i.e., theatrical murder) to its opponents. However, closer examination suggests otherwise. Awareness of these poisonings resulted from operational failures, including circumstances that prevented immediate lethality and allowed the use of poison to be detected and investigated. Evidence highlights that the dose in the 2020 Navalny case was lethal and his survival apparently resulted from unanticipated factors. In both the Skripal and the first Navalny attempts, had the agents produced rapid death, the actual cause likely would have been obscured. Yulia Skripal’s unintended Novichok exposure, however, enabled rapid detection in the United Kingdom, followed by laboratory confirmation. Notably, the first responders in Salisbury initially suspected the Skripals were suffering a drug overdose. Likewise, in Navalny’s case, the poisoning was confirmed only because he was medically evacuated to Germany. If the dosage had been correct and Navalny had not received prompt emergency care, he likely would have succumbed on the plane or shortly after landing. In this scenario, he would not have been taken to Germany, where Novichok was discovered in his body.
The pattern applies to the 2024 Navalny assassination. If the objective had been to produce a visible and attributable signal, the use of a signature agent such as Novichok would have been more consistent than the choice of a nonclassical and weakly traceable toxin, given that laboratories would have tested for Novichok first. Russian authorities also likely did not anticipate that biological samples would be transferred abroad and analyzed in Organisation for the Prohibition of Chemical Weapons laboratories.
In nearly every case, claims that messaging or theatrical murder fail the parsimony test. Simply, the messaging-only hypothesis requires too many unvalidated, unsupported assumptions. The principle that assassinations’ primary aim is the death of the target (death-only) is parsimonious. The most parsimonious explanation is that, while death is the primary goal, messaging can be a second- or third-order effect, especially if the operation is discovered because the operation has failed.
The narrative that Moscow seeks to “send a message” also tends to cast Russia as the state most associated with chemical weapons assassinations. Recent history, however, shows that the use of poisons and toxins in assassinations has been far more widespread. Since 1946, at least 16 states have been documented as having planned or attempted poison or toxin assassinations, with over 100 known incidents in total. These cases involve both authoritarian and democratic regimes, including the Soviet Union (from the late 1940s to the 1980s), the United Kingdom (1950s), the United States (1960s), France (1950s to the 1960s), Israel (1950s to the 2000s), Czechoslovakia (1950s to the 1970s), Yugoslavia (1960s), East Germany (1970s), Bulgaria (1970s), Chile (1970s), Rhodesia (1970s), Iraq (1970s to the 1990s), apartheid South Africa (1980s to the 1990s), Iran (1990s), Russia (2000s to the 2020s), and North Korea (2017). The recourse to these compounds in targeted assassination is therefore not ideologically specific but stems from the properties of the weapons themselves.
These documented cases span multiple stages of assassination operations — from planning and preparation to attempted assassinations, including the 2018 Skripal and 2020 Navalny poisonings, through to successful killings such as Navalny’s death in 2024. Such operations vary in form and method, ranging from political murder and extrajudicial killing to covert assassination. Their primary rationale, however, remains the elimination of regime opponents, without the possibility of tracing responsibility back to the state. These cases directly contradict the theatrical narrative often associated with recent Russian poison and toxin assassination operations.
This logic is most clearly illustrated by apartheid South Africa, the most extensively documented case of state assassinations using poisons and toxins to date, with 27 known operations, broadly comparable to the combined Soviet and Russian record. Research conducted within apartheid’s chemical and biological warfare program, Project Coast, shows a sustained focus on the weaponization of chemical weapons agents and delivery methods designed to ensure covert lethality, a natural-appearing cause of death, and plausible deniability, including toxins concealed in everyday objects such as umbrellas, screwdrivers, cigarettes, and food or drink containers. Further examination of known chemical weapon assassination operations, even when most cannot be directly linked to Project Coast, indicates that they were conceived to preclude attribution to the apartheid regime. This is illustrated by the poisoning of clothing abroad in the failed assassination attempts against former head of the Dutch anti-apartheid movement Conny Braam in Lusaka and Harare (1987), for which the agent remains unknown, and the confirmed poisoning of Reverend Frank Chikane’s belongings at the airport in Johannesburg, which caused him to fall ill outside the country, first in Namibia and then in the United States (1989), mirroring the 2020 Navalny case.
Apartheid-era political responses, once such cases became public, combining denial with intimidation or retaliation, further illustrate this concealment logic, as in the story of anti-apartheid student activist Siphiwo Mthimkhulu, poisoned with thallium in prison custody in 1981. After his release, he discovered he was poisoned, prompting a public campaign and legal action against authorities. He was, however, shortly thereafter, abducted and killed by the security police, suggesting an effort to suppress exposure of his poisoning.
Historically, these assassination operations have rarely been publicly acknowledged by the states involved. Almost all known operations have come to light through operational failures, including dosing errors that leave victims alive and able to report their illness. Agents have then often been identified or confirmed through foreign medical analysis of biological samples, as in Russian cases, but also in apartheid-era cases such as those of Mthimkhulu (United Kingdom) and Chikane (United States). Beyond operational failures, knowledge of Soviet and apartheid South African chemical weapons assassination programs and associated operations derives largely from recorded testimony, notably that of Soviet defectors and post-apartheid inquiries into Project Coast conducted by the Truth and Reconciliation Commission. The United States use of poisons and toxins was not revealed until the 1975 Church Committee, more than a decade later.
Successful operations, by contrast, leave little trace or are difficult to investigate: Victims may not be believed, poisoning may go unsuspected, difficulty of diagnoses, biological samples may never be obtained, collected too late, or the victim ultimately dies without suspicion. The goal is, as one author has described it, a “silent death,” or as a French paper on assassination described it, pas vu, pas pris (“not seen, not done”). This pattern suggests that documented cases represent only a fraction of state assassinations using lethal compounds, and that both poisonings number and the number of states involved is likely to be far higher.
Once the argument that states resort to these compounds in targeted assassinations to “send a message” is set aside, it becomes possible to examine the factors that may motivate a state to employ such weapons in these assassination operations.
First, a state may resort to poisons and toxins for operational advantages. Owing to their intrinsic properties, they allow covert targeting with difficult detection, as these compounds are silent, odorless, and colorless, and can be delivered through everyday, dual-use contact vectors such as personal items, food, or everyday objects. This enables attacks against hard targets, including well-defended or otherwise inaccessible individuals, often in non-permissive security environments. Chemical weapons can also produce delayed clinical effects, mimic natural illness, or create natural-appearing causes of death, hindering detection and allowing death to occur outside the territory of the responsible state.
Second, such assassinations offer significant advantages in terms of deniability and attribution. Because the cause of death is often extremely difficult to establish with certainty, the use of such weapons can obscure political responsibility and facilitate denial. Ultimately, the objective is for the death to appear natural and devoid of apparent political meaning.
Third, victims may not suspect poisoning or, worse, may not be believed, owing to the perceived implausibility of such an attack. Even when suspicion arises, establishing exposure requires timely access to specialized laboratories capable of appropriate analysis, often limited to Organisation for the Prohibition of Chemical Weapons-designated facilities.
Fourth, delayed effects allow the assassins to escape arrest and interrogation by law enforcement on the scene. We have seen this recently in the Litvinenko and Skripal cases.
Finally, limited political consequences may encourage states to resort to the use of poisons or toxins in assassination. Weakening international prohibitions, including under the Chemical Weapons Convention and the Biological Weapons Convention, have reduced deterrence, largely because the consequences of poison use are negligible and short-lived. International responses are often confined to diplomatic expulsions or symbolic sanctions with few tangible consequences for the responsible state.
Given the motivations outlined above, it is increasingly likely that an increasing number of states may in the future resort to these compounds in targeted assassination operations, especially in the context of rising transnational repression.
Historical precedents of deniable assassination operations using poisons and toxins may themselves encourage further state adoption. As explained above, these compounds have been employed in these operations by both authoritarian and democratic regimes. At present, multiple states across regime types are suspected of maintaining research and development activities related to chemical warfare, raising concerns about their potential use in state-sponsored assassination in the expectation of minimal risk of arousing suspicion, unlikely attribution, and perceived deniability. The limited consequences observed in past cases may further increase the perceived attractiveness of such methods. This is reinforced by the Navalny case, which has produced few meaningful repercussions, following the Feb. 2026 announcement.
This limited reaction to Navalny’s death is embedded in a wider normalization of state non-compliance with international law and the growing use of arbitrary state practices, which may further increase the appeal of poison or toxin use in state assassination operations. The erosion of the norms prohibiting the use of chemical and biological weapons has been demonstrated across multiple contexts, including the use or alleged use of chemical weapons in recent intrastate conflicts (Syria, Georgia) and interstate conflicts (Ukraine, Sudan), further reinforcing this broader normalization of their use. The appeal of chemical weapons use is likely further deepened by a permissive international environment characterized by the intensification of armed conflicts, renewed technologically driven arms competition, and the weakening of peace and security mechanisms.
Contemporary scientific and technological advances may also increase the appeal of poison use in assassinations to states. Developments in chemistry and biotechnology, together with emerging delivery methods, including drones, the proliferation of dual-use materials and technologies, the democratization of scientific knowledge and research infrastructures, and the growing use of artificial intelligence, may lower technical and operational barriers to the formulation and covert deployment of toxic agents.
The narrative that Russia resorted to poisonings in the 2018 Skripal, 2020 Navalny, and 2024 Navalny assassination attempts and killings to “send a message” is highly questionable. Knowledge of these operations has derived primarily from operational failures and the subsequent analysis of biological samples in Organisation for the Prohibition of Chemical Weapons laboratories. Russia’s use of poisons in these targeted assassinations is best explained by the capacity of these weapons to enable concealment and obscure attribution. Historical cases, particularly apartheid South Africa, corroborate this pattern.
Moreover, such practices are not confined to Russia but have historically been employed by both authoritarian and democratic regimes. In the current international context, characterized by weak deterrence, norm erosion, and the widespread suspicion of state chemical and biological weapons capabilities, the prospect of more frequent state recourse to poisons in assassination is therefore a growing concern.
Beyond chemical weapons, risks may also extend to biological ones. Advances in biology and genetic engineering raise the possibility that states could, in the future, consider biologically derived or engineered agents capable of increasing selectivity, reducing uncontrolled spread, and producing forms of disease that would be even more difficult to attribute. Such developments would further enhance the appeal of deniable chemical or biological agents to states for use in covert state-sponsored assassination.
Naomi Rio is a PhD candidate in history at the University of Hamburg, co-supervised by Prof. Kathleen Vogel at Arizona State University (ASU). Her research focuses on Project Coast, Apartheid South Africa’s chemical and biological warfare program (CBW). Her broader work examines state-sponsored CBW programs and targeted assassination, as well as proliferation, dual-use technologies, and the erosion of international norms governing their prohibition.
Glenn Cross, Ph.D. is a former deputy national intelligence officer for weapons of mass destruction responsible for biological weapons analysis. He authored Dirty War: Rhodesia and Chemical Biological Warfare 1975-1980. The views expressed here are solely those of the author in his private capacity and do not in any way represent the views, positions, or policies of the U.S. government, including any of its constituent departments, agencies, or entities.
Image: Nano Banana 2
