Introduction
When we talk about the rules in war, it may feel like a contradiction, because how can something as violent as an armed conflict have rules that should be followed? However, the world has collectively agreed on one thing, that using different chemicals as a method of warfare is crossing a line that the international community cannot really come back from. From the mustard gas of World War, I (WWI) to the nerve agents used in modern Middle East conflicts, these weapons are not just used to kill people, but also to terrorise and spread fear among them. This is one of the many reasons why the international community has spent decades writing Treaties like the Geneva Protocol and the Chemical Weapons Convention (CWC) to make sure that these tools stay in the history of books.
There are still many uncertainties around this topic, one of which is that “chemical weapon” is a legal term with a lot of fine print. Some substances, for example, white phosphorus, are in the grey area. On paper, it is often classified as an incendiary or a smoke agent that is used to hide troop movements, but it can stick to the skin and burn through the bone, and its smoke can cause permanent lung damage. When a military uses a substance like this in a place where civilians, those who do not participate in the hostilities, actually live, it starts to feel like a legal loophole that is designed to dodge the label of a war crime. This brings us to the recent reports coming from Southern Lebanon, where the authorities accuse Israel of using chemicals in civilian areas, while the southern Lebanese countryside still bears the ecological scars of an intense campaign by the Israeli military using white phosphorus and incendiary bombs that burned farmland and forests across southern Lebanon and left the soils polluted with heavy metals (The Guardian, 2026). To determine whether this actually counts as a war crime, we have to look at the actual impact on the ground.
This article aims to break down the legal documents that are supposed to prevent this kind of warfare and will look at the specific gaps in the 1993 CWC and how they are being applied today. Then, using the situation in southern Lebanon as a case study, the article will argue that perhaps the international community should stop focusing on what a weapon is called and start focusing more on what it does to human beings.
How the law regulates Chemical Warfare
To understand if using chemicals in a place like Lebanon or anywhere else is a war crime, we must first look at the books. International law is a vast body of Treaties, customary rules, and protocols that have accumulated since the early 1900s. According to the Additional Protocol I (AP I) to the Geneva Conventions, the parties to the conflict have the right to choose methods or means of warfare, but it is not unlimited (AP I, Art. 35 (1)). Modern International Humanitarian Law (IHL) has developed an extensive body of rules prohibiting or regulating the development, possession, and use of certain weapons (means of warfare) and prohibiting or restricting how such weapons can be used, or hostilities can be conducted (methods of warfare).The distinction between these two is important because any weapon can be used in an unlawful manner (Melzer, 2016).
According to the 1868 St Petersburg Declaration, the restrictions and prohibitions on the use of certain weapons were motivated by the desire to protect combatants from disproportionate harm and suffering. It states that the only legitimate object during war is to weaken the military forces of the enemy, and for this purpose, it is sufficient to disable the greatest possible number of men (St Petersburg Declaration, Preamble, 1868). The reasoning of this Declaration later inspired the emergence of one of the most basic principles of IHL, which prohibits employing “weapons, projectiles, and material and methods of warfare of a nature to cause superfluous injury or unnecessary suffering” (AP I, Art. 35(2)). In application of this principle, IHL restricts or prohibits certain types of weapons, the effects of which are excessively cruel regardless of the circumstances (Melzer, 2016). The prohibition against causing superfluous injury or unnecessary suffering also works as a general principle by which all means and methods of warfare have to be measured. The International Court of Justice (ICJ) in its Advisory Opinion on nuclear weapons argued that the prohibition against causing superfluous injury or unnecessary suffering makes it unlawful to cause combatants “harm greater than that unavoidable to achieve legitimate military objectives” (ICJ, Legality of the Threat or Use of Nuclear Weapons, p. 226, para. 78). Therefore, IHL also regulates the use of Chemical, Biological, and Nuclear weapons as a method of warfare.
The use of chemical weapons is regulated and prohibited by several Treaties, including the 1899 Hague Declaration concerning Asphyxiating Gases, the 1925 Geneva Gas Protocol, the 1993 CWC , and the Rome Statute. The prohibition is also considered to be customary law in any armed conflict (CIHL, Rule 74).
Probably the most comprehensive regulatory regime is set out in the 1993 CWC , which defines chemical weapons as “toxic chemicals and their precursors, except where intended for purposes not prohibited,” munitions exclusively designed for the delivery of toxic chemicals and other equipment designed for use with such munitions (CWC, Art. II (1)). Article II (2) of the CWC defines a toxic chemical as “any chemical which through its chemical action on life processes can cause death, temporary incapacitation or permanent harm to humans or animals. This includes all such chemicals, regardless of their origin, or of their method of production, and regardless of whether they are produced in facilities, in munitions, or elsewhere”. The CWC prohibits not only the use of chemical weapons, but also their development, production, acquisition, stockpiling, retention, and transfer. This prohibition applies under any circumstances and can therefore be regarded as absolute (CWC, Art. I(1)). The Convention also prohibits the use of riot-control agents, albeit only as a method of warfare and not for the purposes of law enforcement (CWC, Art. I(5)).
Ultimately, the problem or the reason why we cannot avoid chemical warfare in the twenty-first century is not that we do not have enough laws, but it is that the laws have gaps. While the 1993 CWC does a very good job of banning things like Sarin or other toxic agents, it relies on something called the “general purpose criterion,” which essentially means that the law cares more about why a military used a chemical than what that chemical actually does to a human body. This creates a dangerous loophole for substances like white phosphorus, because it’s primarily designed to create smoke screens or light up a battlefield, and the militaries can argue that they are not using a chemical weapon, even if the results are just as horrific.
However, international law is not just Treaties, there is an old but very important rule called the “Martens Clause,” which was first adopted at the First Hague Peace Conference in 1899 and has since been reformulated and incorporated in numerous international instruments (Melzer, 2016). Martens Clause says that even if a specific weapon is not mentioned in a Treaty, civilians are still protected by the principle of humanity and the dictates of public conscience (AP I, Art 1(2)). The international community must judge any weapon by its impact on society, especially civilians, during armed conflicts.
Case Study: White Phosphorus in Southern Lebanon
White phosphorus is a chemical substance dispersed in artillery shells, bombs, and rockets that ignites when exposed to oxygen (Human Rights Watch, 2024). Its incendiary effects inflict death or cruel injuries that result in lifelong suffering, it can set homes, agricultural areas, and other civilian areas on fire. As mentioned above, under IHL, the use of white phosphorus is unlawfully indiscriminate in populated areas and otherwise does not meet the legal requirements to take all feasible precautions to avoid civilian harm. Although there can be lawful uses, it must never be fired at, or in close proximity to, a populated civilian area or civilian infrastructure, due to the high likelihood that the fires and smoke it causes will spread.
The public archive documented 248 white phosphorus strikes in South Lebanon between October 2023 and November 2024 (White Phosphorus Info). Reportedly, in October 2023, the Israeli army fired artillery shells containing white phosphorus in military operations along Lebanon’s southern border (Amnesty International, 2023). According to Amnesty International, the attack on the town of Dhayra must be investigated as a war crime because it was an indiscriminate attack that injured at least nine civilians and damaged civilian objects, and was therefore unlawful (Amnesty International, 2023). Reportedly, after the Israeli military used the chemical, nine people were suffering from shortness of breath and coughing, which was due to inhaling white phosphorus. The medical experts stated that “the most severe effects of white phosphorus are the dermal or skin effects, which can include second and third degree burns that can lead to very significant, deep necrotic and full thickness burns, and the exposure to white phosphorus smoke could lead to acute upper respiratory damages including shortness of breath, fast breathing, coughing, but it could also have delayed effects” (Human Rights Watch, 2024). Moreover, by June 2024, the situation in Southern Lebanon had evolved from isolated incidents into what could be described as a widespread and systematic risk to civilian life (Human Rights Watch, 2024). The investigation by Human Rights Watch confirmed that white phosphorus had been deployed across at least 17 municipalities in Lebanon, with airbus munitions landing directly on residential buildings in five of those towns.
By late 2025, an investigation led by an open-source researcher revealed that the “incidental” damage of these strikes has become a permanent feature of the southern Lebanese landscape (France 24, 2025). A study by the researcher, Ahmad Baydoun, mapped hundreds of verified incidents from October 2023 to November 2024, showing that nearly half of the strikes hit residential areas. Beyond the immediate horror of the burns, the study also highlighted that a sample of soil can look perfectly normal, only to burst into flames the moment a farmer’s plough hits it or children dig into the dirt, “a year after the initial strike, the fragment started emitting toxic smoke again, demonstrating the ongoing danger of people’s lives and livestock-” said Ahmad Baydoun. It has created a kind of environmental trauma where people are afraid of their own land. For the families in the south, the olive groves that once represented their history and livelihood are now seen as toxic zones, effectively turning their homes into a place that they can no longer trust (France 24, 2025).
Back in 2013, the Israeli military made a public commitment to move away from using white phosphorus after the international backlash over its use in Gaza during Operation Cast Lead (Human Rights Watch, 2024). During that 2008-2009 conflict, the military fired hundreds of phosphorus shells into crowded areas, hitting schools and hospitals and leaving behind a trail of civilian casualties that could not be ignored. While the government officially maintained that these were just “smokescreens,” the High Court in Israel eventually pressured the military to change its tune. This led to a promise that the IDF would develop non-phosphorus alternatives and eventually phase out the chemical, they even told the High Court of Justice that they would only use the substance in “extreme exceptions” under very specific conditions (Human Rights Watch, 2024). However, from today’s point of view, this was more of a pledge than a formal change in law, and as the recent events in Lebanon show, that “extreme exception” seems to have become the rule again. Even though the IDF knew the risks and claimed to be looking for a clearer way to hide the troop movements, the military never fully closed the door on using a chemical that they already knew was devastating to civilian life. Israel’s widespread use of white phosphorus in South Lebanon clearly highlights the need for stronger international law on incendiary weapons.
Conclusion
The evidence from Southern Lebanon serves as a stark reminder that the current legal frameworks are struggling to keep pace with the realities of modern warfare. Throughout this article, it has been highlighted that while Treaties like the CWC were designed with the noble intent of protecting humanity, they are currently riddled with loopholes that allow devastating substances to be used in populated areas. By calling white phosphorus “smokescreen,” militaries can bypass the strict bans on chemical and incendiary weapons, even though the chemical acts as a terrifying agent of burn, suffocation, and long-term environmental poisoning once it touches oxygen.
The current legal regime focuses more on the primary design and stated intent of a weapon rather than its actual effect on human life and the environment. To ensure that the principles of humanity mentioned in the Martens Clause are more than just a legal fallback, several urgent changes are necessary.
Ultimately, if the international community keeps putting military tactics ahead of the shared sense of what is right and wrong, they are basically turning the ban on chemical warfare into a hollow promise from the past. We only have to look at the scorched hills of Lebanon to see that the current laws are not working.
Bibliography
Legal Instruments and Treaties
Chemical Weapons Convention (1993). Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction. https://ihl-databases.icrc.org/en/ihl-treaties/cwc-1993 accessed February 15, 2026.
International Committee of the Red Cross (ICRC). (2005). Customary International Humanitarian Law, Volume I: Rules.
International Court of Justice (ICJ). (1996). Legality of the Threat or Use of Nuclear Weapons. Advisory Opinion, I.C.J. Reports 1996. https://www.icj-cij.org/case/95 accessed February 15, 2026.
Protocol Additional to the Geneva Conventions of 12 August 1949 (Protocol I). (1977). https://ihl-databases.icrc.org/en/ihl-treaties/api-1977?activeTab= accessed February 15, 2026.
St. Petersburg Declaration. (1868). Declaration Renouncing the Use, in Time of War, of Explosive Projectiles Under 400 Grammes Weight. https://ihl-databases.icrc.org/en/ihl-treaties/st-petersburg-decl-1868?activeTab= accessed February 15, 2026.
Human Rights Reports
Amnesty International. (31 October, 2023). Lebanon: Evidence of Israel’s unlawful use of white phosphorus in southern Lebanon as cross-border hostilities escalate. https://www.amnesty.org/en/latest/news/2023/10/lebanon-evidence-of-israels-unlawful-use-of-white-phosphorus-in-southern-lebanon-as-cross-border-hostilities-escalate/ accessed February 15, 2026.
Human Rights Watch. (June 5, 2024). Lebanon: Israel’s White Phosphorus Use Risks Civilian Harm. https://www.hrw.org/news/2024/06/05/lebanon-israels-white-phosphorous-use-risks-civilian-harm accessed February 15, 2026.
White Phosphorus Info. (n.d.). Public Archive: Documented White Phosphorus Strikes in Lebanon. https://whitephosphorus.info/ accessed February 15, 2026.
Articles
France 24. (December 3, 2025). Study reveals persistent danger of Israeli white phosphorus strikes in southern Lebanon. https://www.france24.com/en/middle-east/20251203-study-reveals-persistent-danger-israeli-white-phosphorus-strikes-southern-lebanon accessed February 15, 2026.
The Guardian. (February 5, 2026). Israel accused of spraying cancer-linked herbicide on farms in southern Lebanon. https://www.theguardian.com/world/2026/feb/05/israel-accused-of-spraying-cancer-linked-herbicide-on-farms-in-southern-lebanon accessed February 15, 2026.
The National WWI Museum and Memorial. (n.d.). Spotlight: First Usage of Poison Gas. https://www.theworldwar.org/learn/about-wwi/spotlight-first-usage-poison-gas accessed February 15, 2026.
Books
Melzer, N. (2016). International Humanitarian Law: A Comprehensive Introduction. International Committee of the Red Cross.
