White Phosphorus – what harm does it cause?

White phosphorus is a wax-like chemical substance that ignites spontaneously when exposed to oxygen. It burns at extremely high temperatures and continues to burn as long as it is exposed to air. Using it as an incendiary weapon specifically targeted at civilian populations is illegal – yet, this is exactly what Israel has recently been accused of doing.

International observers like Human Rights Watch and the UN have documented airburst WP munitions exploding directly over residential homes in towns like Yohmor, Lebanon, causing human injuries and fires in civilian cars and buildings. While the Israeli military maintains that these shells are used legally to create smokescreens, observers argue that deploying them in populated areas is inherently “indiscriminate” and illegal under international law, especially since non-incendiary alternatives exist.

WP is distinct from most other conventional weapons because it causes harm through three simultaneous channels: thermal (heat), chemical (corrosive), and systemic (poisoning):

• The most immediate harm is the thermal burn. White phosphorus ignites at around 30°C and burns at up to 800°C. Because WP is lipid-soluble, it melts through skin and fat layers and “eats” its way down until it hits bone. If a fragment of WP is embedded in a wound, it will stop burning once it is completely cut off from oxygen. If a surgeon then opens the wound to remove it, the phosphorus re-ignites upon contact with the air, potentially injuring medical staff.
• Even a small burn covering less than 10% of the body can be fatal because the body absorbs WP into the bloodstream. This causes a massive shift in electrolytes, specifically causing hypocalcemia. This can lead to fatal heart arrhythmias or cardiac arrest. In addition, WP is a potent toxin that causes “fatty degeneration” of the liver and renal failure. Victims may thus survive the initial burn only to die days later from internal organ failure.
• When WP burns, it produces a thick, white smoke of phosphorus pentoxide. Inhaling this smoke reacts with the moisture in the lungs to form phosphoric acid. This causes severe chemical burns to the throat and lungs, leading to pulmonary edema and eventually suffocation.
• WP particles can remain dormant in the soil. If a farmer plows the field and unearths a fragment months later, it can reignite and start a fire or cause injury.

In addition WP also destroys the planet. While the phosphorus pentoxide smoke dissipates, the elemental phosphorus in water or soil is toxic to aquatic life and birds. In waters with low oxygen, WP can persist for years.

Other than Israel, the following countries have recently used WP in these conflicts:

• Iraq (2004): During the Second Battle of Fallujah, U.S. forces used WP to “flush out” insurgents from hidden positions so they could be targeted with high explosives—a tactic known as “shake and bake.” After initial denials, the Pentagon confirmed its use as an incendiary weapon against combatants.
• Vietnam & Korea: The U.S. used WP extensively in both conflicts for smoke screens, marking targets, and as an anti-personnel weapon.
• Syria (2017): During the battle to retake Raqqa from ISIS, the U.S.-led coalition was accused by Human Rights Watch of using air-dropped WP, which raised concerns about the risk to civilians in the densely populated city.
• Ukraine (2022–2026): Russia has been repeatedly accused by Ukrainian officials and international observers of using WP or similar incendiary munitions (like thermite) in cities such as Mariupol, Bakhmut, and more recently in Donetsk (2026). Russia typically maintains that its munitions are for illumination or smoke, or denies their use entirely.
• Chechnya: Russian forces used WP during the First and Second Chechen Wars (1994–2000), particularly during the siege of Grozny.
• Syria: Working alongside the Syrian government, Russian forces were frequently accused of using incendiary weapons, including phosphorus, on rebel-held areas.
• Nagorno-Karabakh (2020): During the 44-day war, Armenia accused Azerbaijan of using white phosphorus to burn down forests where Armenian soldiers were allegedly sheltering. Azerbaijan denied this and countered with its own accusations that Armenia had used the substance in 2016 and 2020.
• Yemen (2016): The Saudi-led coalition was reported to have used U.S.-supplied white phosphorus in its campaign against Houthi rebels. While the coalition claimed it was for marking and smoke screens, images emerged suggesting it was being used near civilian areas.