There has been widespread international outrage at Israel’s attack on Nasser hospital in Khan Younis, northern Gaza, on August 25. The attack took the form of a “double tap” strike. The first attack killed at least one person, then – as medics, journalists and other responders rushed to the scene – a second attack on the same location killed another 20 people. This included five journalists and several medical staff treating people injured in the first attack.

Israel’s prime minister, Benjamin Netanyahu, has called the incident a “tragic mishap”. But whether or not the attacks on the hospital were intentionally directed, the double tap tactic almost certainly falls under those acts of war prohibited by the law of armed conflict and could constitute a war crime on that basis alone.

Whether or not charges specifically relating to the attacks on Nasser Hospital are ever brought, it’s an opportunity to examine how international law operates in situations like this.

Who is fighting who, and why it matters

That the hostilities in Gaza constitute, in international law, an “armed conflict” is beyond doubt. That means that there are grounds for the application of the law of armed conflict (LOAC) – or as it is also known, international humanitarian law.

If we see today’s conflict as being between Israel and Hamas, then it would be a non-international conflict because it would not be between two or more states. But if it is between Israel and Palestine then, whether or not Israel recognises Palestine as a valid state, it would be international. In May 2024, International Criminal Court (ICC) prosecutor Karim Khan caused some controversy when he said that it was both, running in parallel.

This issue is important because the rules covering international and non-international armed conflict are not the same. The rules on international armed conflict are older and more detailed. This also means that there are separate lists of international and non-international war crimes in the Rome Statute, the treaty that established the ICC. But the LOAC rules relevant to a double-tap attack are similar enough in both types of conflict that we can postpone coming to a conclusion on this until such as time as war crime charges are actually brought.

Law of armed conflict

The first essential feature of LOAC is that it is all based on the idea that the means (weapons) and methods (tactics) used in an armed conflict are “not unlimited”. That is why some weapons are banned – chemical weapons, for example. When it comes to tactics it is, for example, unlawful to order to “take no prisoners”.

There are other even more fundamental rules on methods that govern the conduct of hostilities.

The main rules on hostilities are often said to be humanity, necessity, distinction and proportionality. Humanity is about not inflicting unnecessary suffering. Necessity requires that in applying the other rules a commander should be able to do what they need to “win”, but no more than that. Distinction requires that only lawful objectives should be targeted for attack. Proportionality requires that when a lawful objective is attacked, the expected “collateral damage” should not be excessive to the expected military advantage of the attack.

It’s important to note that a judgement on proportionality must be made before a military action is launched and during an attack “constant care” should be taken that the situation really is what the military commander thought it was when they ordered the attack. That rule is meant to minimise accidents.

Double-tap attacks

Distinction and proportionality are the key principles for looking at a “double-tap attack” such as the one on August 25. First, applying the rule on distinction, there are only very limited circumstances in which a hospital could ever be a lawful target. Hospitals are marked out for special protection under the Geneva Conventions. The same goes for journalists, who are protected alongside all other civilians, as long as they do not become engaged in fighting.

Further to this, it would be reasonable to expect that after a lethal attack medics would attend the site, and journalists might want to cover it. Launching the second attack could therefore be said to be either intentionally directed against the medics and journalists or, at the very least, uncaring as to whether both lawful and unlawful targets might be killed. That is known as an “indiscriminate” attack. So it also violates the rule on distinction. It is also difficult to see how the second attack could have been accidental.

And even if it were argued that the hospital was a lawful target, for example due to being used by Hamas fighters to stage attacks on the Israeli forces, the collateral damage was almost certainly going to be vast. So, for that reason, it would violate the rule on proportionality.

Israel is a state party to the Geneva Conventions of 1949, which require that “grave breaches” of their rules are investigated and prosecuted. Alternatively, and whether or not the conflict is found to be international or non-international, the Rome Statute provides a solid basis for the above violations of LOAC to be prosecuted as war crimes at the International Criminal Court.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: James Sweeney, Lancaster University

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James Sweeney does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.