The recent news that the death of Russian opposition leader Alexei Navalny was caused by epibatidine, a toxin from a South American frog, has renewed interest in the use of poisons and toxins by states in assassinations, War on the Rocks writes.
While the use of such compounds by states has a long history, the erosion of norms prohibiting assassinations and chemical and biological weapons increases the likelihood of future assassinations using poisons and toxins. As seen in the recent attacks on the Iranian leadership in Operation "Epic Fury" and since the assassinations of prominent Iranian nuclear scientists, including Mohsen Fakhrizadeh, the norm for killing has collapsed.
The norms against the use of chemical and biological weapons, especially in killing, have weakened significantly to the point that poisons and toxins are likely to become just another tool in the killer's arsenal. To date, the lackluster international response to the use of poisons and toxins in killing only ensures continued international acquiescence.
The question, then, is why do states use poisons and toxins to eliminate their opponents? Are these compounds in targeted killings intended to cover up the act itself, or are they intended to signal harm to those who oppose the regime?
On February 14, 2026, France, Germany, the Netherlands, Sweden, and the United Kingdom issued a joint statement concluding that Navalny’s death, which occurred on February 16, 2024, while in custody, was the result of epibatidine. Analyses conducted in laboratories in these countries confirmed the presence of the substance, which is banned under the Chemical Weapons Convention. This highly toxic compound was most likely synthesized by Russian scientists, thus implicating the Russian government. Following this announcement, there was speculation that the use of epibatidine in Navalny's assassination was to "send a message".
This narrative is rooted in the successful Russian assassination of former Russian intelligence officer Alexander Litvinenko in November 2006, as well as in two recent failed assassination attempts: that of former Russian military intelligence officer Sergei Skripal, who also affected his daughter, in Salisbury on March 4, 2018, and that of Navalny on a flight to Moscow on August 20, 2020. The choice of this substance contributed to the perception of Novichok as a distinctive "Russian signature" used by Moscow to signal intent, while reinforcing the narrative that places Russia at the center of state-sponsored use of poisons and toxins in assassinations. Taken together, the use of rare or unusual materials has led some to suggest that the purpose was to send messages.
However, neither the murder of Litvinenko, nor the attempted assassination of Skripal in 2018, nor that of Navalny in 2020 and his successful assassination in 2024 support this interpretation. A closer analysis shows that the main goal was the elimination of an opposition figure without disclosure or attribution of guilt, rather than a theatrical signal of this. The historical record of state assassinations further supports this conclusion. It is therefore necessary to revisit why states prefer poisons and toxins in targeted killings and to what extent other states, besides Russia, may be involved in such covert operations.
The Skripal and Navalny Cases: From "Novichok Signature" to invisible epibatidine
Skripal spied for British intelligence and was arrested and imprisoned in Russia in 2006. Following a spy swap in 2010, Skripal was transferred by British authorities to Salisbury, England, where he lived until he was the victim of an attempted assassination with Novichok. On the morning of 4 March 2018, Skripal left his home with his daughter, who had flown in from Moscow the day before to visit him, unaware that the doorknob on the front door had been contaminated with Novichok in an attempt to kill him. After initially leaving, his daughter Yulia briefly returned to the house, also came into contact with the contaminated doorknob and was exposed to the nerve agent. Both were found unconscious on a bench in central Salisbury. They were taken to an emergency room and survived after intensive medical treatment. Subsequent analyses by the laboratories of the Organization for the Prohibition of Chemical Weapons confirmed the use of Novichok. It is clear that Skripal was the sole target, and Yulia was only affected because the killers did not consider re-entering the house.
Navalny is Vladimir Putin's most prominent critic. On August 20, 2020, before boarding a flight from Tomsk to Moscow, the oppositionist's clothes in his hotel room in Tomsk were contaminated with Novichok. As he fell seriously ill shortly after takeoff, the plane made an emergency landing in Omsk, where he received initial emergency care. He was subsequently evacuated to Germany, where he underwent intensive care. Laboratory tests later confirmed Novichok poisoning.
The use of these compounds in targeted killings is not ideologically specific, but stems from the properties of the weapons themselves.
After his recovery, Navalny blamed Putin for the attack and implicated Russia's Federal Security Service. He returned to Moscow in 2021 and was promptly arrested and imprisoned. After being convicted on a number of charges, Navalny remained in custody until he was found dead in his cell on February 16, 2024. Russian authorities attributed Navalny's death to "sudden death syndrome" - a broad term for sudden 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, the ultimate cause of death would have remained unknown.
In all three cases, one theory is that Russia used exotic compounds to "send a message" (i.e., staged assassination) to its opponents. However, closer examination suggests otherwise. The discovery of these poisonings was the result of operational failures, including circumstances that prevented immediate lethality and allowed the use of poison to be discovered and investigated. The evidence suggests that the dose in the 2020 Navalny case was lethal and his survival was clearly the result of unforeseen factors. As in the Skripal attempt and the first Navalny attempt, if the nerve agent had caused a rapid death, the actual cause would likely have remained hidden. However, Yulia Skripal’s inadvertent exposure to Novichok allowed its rapid detection in the UK, followed by laboratory confirmation.
Curiously, first responders to the Salisbury case initially suspected that the Skripals had suffered a drug overdose. Similarly, in the Navalny case, the poisoning was only confirmed because he was evacuated to Germany for treatment. If the dose had been correct and Navalny had not received prompt emergency care, he would likely have died on the plane or shortly after landing. In that scenario, he would not have been flown to Germany, where Novichok was found in his body.
This pattern also applies to Navalny’s assassination in 2024. If the goal was to produce a visible signal and make the assassination attributable, using an iconic agent like Novichok would have made more sense than choosing a non-classical and poorly traceable toxin, given that laboratories would have conducted studies specifically on Novichok first. Russian authorities likely did not anticipate that biological samples would be transferred abroad and analyzed in OPCW laboratories.
In almost every case, claims of sending messages or staged assassination fail the parsimony test. Simply put, the message-only hypothesis requires too many untested, unsupported assumptions. The principle that the primary goal of the assassinations is the death of the target (only death) is parsimonious. The most parsimonious explanation is that while death is the primary goal, sending messages may be a secondary effect, especially if the operation is discovered because it failed.
Historical evidence of state-sponsored chemical weapons assassinations
The narrative that Moscow is seeking to "send a message" also tends to portray Russia as the country most closely associated with chemical weapons assassinations.
However, more recent history shows that the use of poisons and toxins in assassinations has been much more widespread. Since 1946, at least 16 countries have been documented as having planned or attempted to carry out assassinations using poison or toxins, with a total of over 100 known incidents.
These cases include both authoritarian and democratic regimes, including the Soviet Union (late 1940s to 1980s), the United Kingdom (1950s), the United States (1960s), France (1950s to 1960s), Israel (1950s to 2000s), Czechoslovakia (1950s to 1970s), Yugoslavia (1960s), East Germany (1970s), Bulgaria (1970s), Chile (1970s), Rhodesia (1970s), Iraq (1970s to 1990s), apartheid South Africa (1980s to 1990s), Iran (1990s), Russia (2000s to 2020s) and North Korea (2017).
The goal is "silent death", or, as described in a French report on the killings - pas vu, pas pris ("unseen, untaken")
The use of these compounds in targeted killings is therefore not ideologically specific, but stems from the properties of the weapons themselves. The documented cases cover multiple stages of assassination operations - from planning and preparation to assassination attempts, including the poisonings of Skripal in 2018 and Navalny in 2020, to successful assassinations, such as Navalny's death in 2024. Such operations vary in form and method - from political assassinations and extrajudicial executions to secret assassinations. However, their main rationale remains the elimination of opponents of the regime, without the possibility of tracing responsibility back to the state. These cases directly contradict the theatrics theory often associated with recent Russian poison and toxin assassination operations.
This logic is most clearly illustrated by South Africa during apartheid - the most extensively documented case of state assassinations using poison and toxin to date, with 27 known operations, comparable to the combined Soviet and Russian experience.
Research conducted under the apartheid chemical and biological warfare program - Project Shore - shows a sustained focus on the use of chemical weapons and execution methods designed to provide covert lethality, a natural-looking cause of death, and plausible deniability, including toxins hidden in everyday objects such as umbrellas, screwdrivers, cigarettes, and food or beverage cans. Further examination of the known chemical weapons assassination operations, even when most cannot be directly linked to Project Shore, shows that they were designed to exclude attribution to the apartheid regime. This is illustrated by the poisoning of clothes abroad in the failed assassination attempts on former Dutch anti-apartheid leader Connie Braam in Lusaka and Harare (1987), for which the agent remains unknown, and the confirmed poisoning of Reverend Frank Chickane's belongings at Johannesburg airport, which caused his illness abroad - first in Namibia and then in the United States (1989), and is analogous to that of Navalny since 2020.
After such cases became public, apartheid-era political reactions, combining denial with intimidation or revenge, further illustrate this logic of cover-up, as in the story of anti-apartheid student activist Sifivo Mtimkulu, who was poisoned with thallium in prison in 1981. After his release, he discovered that he had been poisoned, leading to a public campaign and legal action against the authorities. Shortly afterwards, however, he was abducted and killed by the security police, in what is believed to be an attempt to prevent the discovery of his poisoning.
Historically, these assassination operations have rarely been publicly acknowledged by the countries involved. Almost all known operations have come to light due to operational failures, such as dosing errors that left the victims alive so that they could report their illness. The agents have often been identified or confirmed by foreign medical analysis of biological samples, as in the Russian cases, but also in apartheid-era cases such as those of Mtimhulu (United Kingdom) and Chikane (United States). Apart from operational failures, knowledge of the Soviet and South African chemical weapons assassination programs and related operations derives largely from recorded testimony, particularly from Soviet defectors and post-apartheid investigations of Project Shore, conducted by the Truth and Reconciliation Commission. The use of poisons and toxins by the United States was not revealed until the Church Commission in 1975, more than a decade later.
In contrast, successful operations leave little trace or are difficult to investigate: victims may be distrusted, poisoning may go unsuspected, diagnoses may be difficult, biological samples may never be obtained, collected too late, or the victim may eventually die without suspicion. The goal is, as one author has called it, "silent death", or, as described in a French report on the killings, pas vu, pas pris ("unseen, untaken"). This pattern suggests that the documented cases represent only a small fraction of state-sponsored assassinations using lethal compounds, and that both the number of poisonings and the number of states involved are likely much higher.
Motives for State-Sponsored Chemical Weapons Assassinations
Once the argument that states resort to these compounds in targeted killings to "send a message" is set aside, it becomes possible to examine the factors that might motivate a state to use such weapons in assassination operations.
First, a state may resort to poisons and toxins for operational advantage. Due to their inherent properties, they allow for a covert attack that is difficult to detect, as these compounds are silent, odorless, and colorless, and can be delivered through everyday dual-use contact media such as personal belongings, food, or household items. This allows attacks on difficult targets, including well-protected or otherwise inaccessible individuals, often in adverse security environments. In addition, chemical weapons can cause delayed clinical effects, mimic natural diseases, or create natural-looking causes of death, which hinders detection and allows death to occur outside the territory of the responsible state.
Second, such killings offer significant advantages in terms of possibilities for denial and attribution of blame. Since 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 aim is to make the death appear natural and devoid of any apparent political significance.
Such practices are not limited to Russia, and have historically been used by both authoritarian and democratic regimes.
Third, victims may not suspect poisoning or, worse, may not be believed due to the perceived implausibility of such an attack. Even when doubt arises, establishing exposure to a poison requires timely access to specialized laboratories capable of performing appropriate analysis, often limited to sites designated by the Organization for the Prohibition of Chemical Weapons.
Fourth, delayed effects allow killers to avoid arrest and questioning by law enforcement agencies on the spot. This was the case recently in the poisonings of Litvinenko and Skripal.
Finally, limited political consequences can encourage states to resort to the use of poisons or toxins for assassination. The weakening of international prohibitions, including under the Chemical Weapons Convention and the Biological Weapons Convention, has reduced deterrence, largely because the effects of poisons are minor and short-lived. International responses are often limited to diplomatic expulsions or symbolic sanctions with few tangible consequences for the responsible state.
Looking ahead: The enduring appeal of state use of poisons and toxins
Given the reasons outlined above, it is increasingly likely that more states will resort to these compounds in targeted assassination operations in the future, especially in the context of increasing transnational repression.
Historical precedents for deniable assassination operations with poisons and toxins may themselves encourage their further adoption by states. As explained above, these compounds have been used in these operations by both authoritarian and democratic regimes.
Currently, multiple states with different regime types are suspected of maintaining research and development related to chemical weapons, raising concerns about their potential use in state-organized assassinations with the expectation of minimal risk of arousing suspicion, unlikely attribution of authorship, and perceived possibility of denial. The limited consequences observed in past cases may further increase the perceived appeal of such methods. This is reinforced by the Navalny case, which did not result in significant consequences after its announcement in February 2026.
This limited response to Navalny’s death is embedded in a broader normalization of state failure to comply with international law and the increasing use of arbitrary state practices, which may further increase the appeal of using poisons or toxins in state assassination operations. The erosion of norms prohibiting the use of chemical and biological weapons is becoming evident in multiple contexts, including the use or alleged use of chemical weapons in recent intra-state conflicts (Syria, Georgia) and inter-state conflicts (Ukraine, Sudan), further reinforcing this broader normalization of their use. The appeal of chemical weapons is likely to be further enhanced by the enabling international environment, characterized by the escalation of armed conflict, the renewal of technologically driven arms races, and the weakening of peace and security mechanisms.
Modern scientific and technological advances may also increase the appeal of the use of poisons in assassinations for states. Developments in chemistry and biotechnology, along with emerging delivery methods including drones, the proliferation of dual-use materials and technologies, the democratization of scientific knowledge and research infrastructures, and the increasing use of artificial intelligence, may reduce the technical and operational barriers to the covert deployment of toxic agents.
Conclusion
The narrative that Russia resorted to poisonings in the attempted assassinations of Skripal in 2018, Navalny in 2020, and Navalny in 2024 to "send a message" is highly questionable. Knowledge of these operations derives primarily from operational failures and the subsequent analysis of biological samples in laboratories of the Organization for the Prohibition of Chemical Weapons. Russia's use of poisons in these targeted killings is best explained by the capacity of these weapons to allow for cover-up and unclear attribution of responsibility. Historical cases, especially South Africa during apartheid, confirm this pattern.
Furthermore, such practices are not limited to Russia, but have historically been used by both authoritarian and democratic regimes. In the current international context, characterized by weak deterrence, erosion of norms, and widespread suspicion of states’ capabilities to use chemical and biological weapons, the prospect of states resorting more frequently to poisons in assassinations is increasingly troubling.
In addition to chemical weapons, the risks may extend to biological weapons. Advances in biology and genetic engineering raise the possibility that states may in the future consider biologically derived or engineered agents capable of increasing selectivity, reducing uncontrolled spread, and causing forms of disease that would be even more difficult to attribute. Such developments would further increase the attractiveness of chemical or biological agents for use in state-sponsored covert assassinations.