The operation that used pagers and walkie-talkies to kill members of the Lebanese militant group Hezbollah was ingenious – but was it legal?

Certainly, there are those who will argue that it was. That thinking goes like this: Hezbollah has been attacking Israel with rockets, and the pagers and radios purchased by Hezbollah could be expected to be used by the same people involved in decisions to send those missiles. As such, the killings, if carried out by Israel as is widely believed, would appear to be targeted and warranted. While some bystanders may die or be injured, they would likely be associated with Hezbollah, according to this line of thinking.

But that is not the right assessment, according to international law. Under law I have taught for over 40 years, hiding explosives in everyday objects makes them booby traps – and in almost every case, using a booby trap designed to kill is a crime.

Prohibited means of warfare

It is important to affirm that the acts that apparently led Israel to strike Hezbollah are also illegal under international law. In fact, Hezbollah, a nonstate armed group supported by Iran, has no right to use violence of any kind, let alone missile strikes targeting civilians in northern Israel.

Under international law, a nonstate actor gains the right to fight only if it is associated with a regular armed force of a sovereign state involved in armed conflict hostilities. And that is not the case with Hezbollah in Lebanon. This means each Hezbollah missile constitutes the commission of a serious crime.

But that fact does not give rise to any right of Israel to use booby traps in response.

A booby trap is defined by the International Committee of the Red Cross, the body charged with oversight and implementation of the Geneva Conventions and related treaties on the law of armed conflict, as a “harmless portable object” – but redesigned to contain explosive material. They are a prohibited means of warfare and are equally prohibited by law enforcement authorities.

In peacetime, police and other law authorities are restricted to using lethal force only in cases in which a life is immediately in danger. Carefully dismantling a device, adding explosives and sending them on to be used in homes or places of worship, for example, cannot be seen to be saving a life immediately.

And it is peacetime law that applies in Lebanon at this time. There is, under international law, no war currently taking place in Lebanon. Israel is involved in armed conflict hostilities in Gaza, not Lebanon. The intermittent attacks across the Lebanon-Israel border do not constitute hostilities as defined under international law.

Growing list of violations

Even if hostilities were occurring between Israel and Lebanon, as might well happen, Israel would have no right to use booby traps. In hostilities, an adversary’s fighters may be intentionally targeted and killed. Ambushes and other clandestine operations are permitted. And the lives of civilians may be lost in doing so.

But weaponizing an object used by civilians is strictly prohibited in wartime. It is a form of “killing treacherously,” meaning with deception. It is the opposite of carrying weapons openly, as required by the venerable treaty the Hague Convention Annex of 1907 – which is still binding law for all engaged in warfare.

Despite being clearly illegal for over a hundred years, the use of booby traps persists. During the terrorist violence that plagued Northern Ireland for decades, the anti-British Irish Republican Army deployed booby traps, in particular car bombs. Members of the group were regularly prosecuted under U.K. law. Members of the United States military would be prosecuted too if they decided to create and use a booby trap.

The use of booby traps adds to Israel’s growing list of post-Oct. 7 violations of international law. The country itself was the victim of a brutal criminal act by Hamas and other Palestinian armed groups. And international law permits significant, robust responses to such a crime. But it also sets strict conditions and limits – and it clearly holds that the use of booby traps goes beyond those limits.

Mary Ellen O'Connell is affiliated with, in addition to the University of Notre Dame, the Global Commission on Responsible Artificial Intelligence in the Military Domain: https://hcss.nl/gcreaim/