What the Use of White Phosphorus Means in Warfare

There was nowhere for civilians to hide. Billowing above the streets of Gaza, a white cloud spread across the city’s main harbor, plumes of smoke descending from air-dropped munitions. Human rights groups said the fog was from a weapon first used in World War I that violates international norms. Israel said the claim was bunk.

After nearly a week of fighting following Oct. 7, Human Rights Watch said that video footage and witness testimony “verified” the use of white phosphorus in civilian areas, a use of the weapon that rights activists believe should be explicitly banned under international law. The Washington Post confirmed the video, which showed two Israeli 155 mm artillery shells releasing what appeared to be white phosphorus. Israel denied the allegations, calling them “unequivocally false.”

White phosphorus creates light and smoke distractions to help troops conceal their movements. It is packed into an artillery tube or bomb in the form of solid phosphate rocks and fired from the ground or air, igniting upon contact with oxygen and heating up to nearly 1,500 degrees Fahrenheit. The other main type of phosphorus, red phosphorus, is not toxic.

Fired into Gaza, one of the most densely populated areas in the world and home to 2.3 million people, white phosphorus-laced projectiles have a significant chance of hitting innocent bystanders. “Any time that white phosphorus is used in crowded civilian areas, it poses a high risk of excruciating burns and lifelong suffering,” said Lama Fakih, the director for the Middle East and North Africa at Human Rights Watch.

The development comes as the urban battlefield between Israel and Hamas gets more tense, more constrained, and more complex—with Israeli Prime Minister Benjamin Netanyahu still indicating that Israel is preparing for a ground invasion of the Gaza Strip. Investigators observed that at least seven munitions with markings like those on last week’s white phosphorus weapons were seen on Monday in southern Israel, suggesting that those too may be packed with the chemical.

Meanwhile, on Tuesday, a projectile hit a Gaza City hospital, killing an unknown number of Palestinians. Israeli and U.S. intelligence reports indicate that Palestinian Islamic Jihad militants based in Gaza were responsible for the blast.

Retaliation in tit-for-tat battles has escalated, and international and U.S. congressional calls for a cease-fire remain ignored by both sides as Hamas orders Israel to stop all missile strikes and Israel demands that Hamas release all hostages. Introducing white phosphorus to the war would be a new and nasty escalation.

The United States has used white phosphorus projectiles before, in the 2003 Iraq War, and as the head of the international coalition spearheading the fight against the Islamic State in Iraq and Syria.

White phosphorus is not defined as a chemical weapon because its lethality comes primarily from its heat rather than its toxicity. But that distinction makes no difference when it comes into contact with the human body. It can burn tissue down to the bone, cause irreparable respiratory damage, and lead to organ failure. Even minor injuries can quickly become lethal if all white phosphorus rocks are not removed from the body.

The United Nations Convention on Certain Conventional Weapons “prohibits the use of weapons primarily designed to set fire to objects or cause burn injuries against civilians.” White phosphorus’s use would also violate states’ obligation under other international laws to “take all feasible precautions to avoid civilian injury and loss of life,” according to Human Rights Watch.

The use of the weapon would be something of an about-face for the Israeli military, which said more than a decade ago that it would phase out the use of the inflammatory agent in favor of U.S.-made World War II-era M150 smoke projectiles.

Rights groups worry that munitions packed with white phosphorus can do irreparable harm to the human body. “They cause absolutely horrific burns,” said Brian Castner, a weapons investigator for Amnesty International’s crisis team studying the substance.. “It is not a traditional fire. It is a chemical reaction. It can’t be put out with water. And if you live through the burns, it’s a life-changing injury.”

And the fear is that firing white phosphorus from artillery shells, which can miss their targets by a country mile, creates a bigger risk of hitting civilians. “It’s not just a single round that’s hitting a specific place. It’s an airburst that is spreading it over an area,” Castner said. Castner added that the artillery projectiles that Israel fires—potentially carrying white phosphorus—can miss by more than 300 feet at the edge of their effective range.

Yet even the legal language in U.N. documents creates loopholes. Those in favor of allowing militaries to use white phosphorus argue that its primary purpose is to serve as a smokescreen for troop movement, not to burn objects or humans. That nuance would exclude the chemical from U.N. regulations.

White phosphorus weapons “contravene the spirit if not the letter of the law because the whole point is to avoid unnecessary suffering and to minimize civilian casualties,” said Leila Sadat, a former special advisor on crimes against humanity to the prosecutor of the International Criminal Court. “States should hold themselves to the highest possible standard, not the lowest possible standard.”

During the nearly monthlong Gaza War in 2008, known in Israel as Operation Cast Lead, the Israeli military fired around 200 ground-launched white phosphorus munitions into Gaza, according to a 2009 Human Rights Watch report. Dozens of Palestinians were killed and numerous civilian structures—including a school, a hospital, a warehouse filled with aid supplies, and a marketplace—were hit.

The military assured rights groups that the use of white phosphorus in its 22-day war was only as a smokescreen for ground operations. But many activists continued to push for its abolition. In 2013, the Israeli military acknowledged white phosphorus’s deadly effects after a series of petitions to ban the chemical were brought to Israel’s High Court. At that point, Israel said it would no longer use the chemical in populated areas except in two “highly particular circumstances.” These exceptions were not made available to anyone but the judge overseeing Israel’s High Court at the time.

Even if white phosphorus were explicitly listed as banned by the U.N. Convention on Conventional Weapons, Israel would not have to abide by its regulations. That is because although Gaza and the West Bank recognize the convention, Israel does not.