UN Charter and the Basic Rule Against the Use of Force
There are many reasons why many countries may not want to take a clear stance on the validity of Israel’s unprecedented military strikes against Iran. However, the question that everyone in the world must ask is whether these strikes are legal under international law. Article 2(4) of the UN Charter clearly says that states cannot use force in international relations. However, there are some limited exceptions, such as Article 51, which says that a state can use force “if an armed attack occurs,” as long as it is necessary and proportional.
Marko Milanovic, an international lawyer, says that the legal idea of self-defense determines whether a country’s use of force is legal. If Israel can only use force to defend itself against armed attacks, then its current use of force is illegal, since Iran or non-state players acting on Iran’s behalf did not launch an armed attack. So, this view says that Israel’s use of force is unlawful and would be an act of invasion, which is against international law and a war crime.
The Illegality Argument: Did Iran Attack Israel?
What about the argument that Israel’s military activities against Iran are legal because of pre-emptive self-defense? This means that states have the right to use force against an “armed attack” that has not yet happened. The reasoning goes that Iran is almost ready to get the technology it needs to make nuclear weapons, and that once it does, its leaders have promised that they will destroy Israel. Israel defends its war against Iran by saying that it is necessary to stop Iran from building a nuclear weapon.
There is disagreement about pre-emptive self-defense in international law because supporting the use of force against a planned armed attack goes against Article 51. However, international lawyers like Rosalyn Higgins say that it would not make sense to make a state wait for an armed attack to happen before it can protect itself.
Understanding the Legal Debate Around Preemptive Self-Defense
Even though the right to pre-emptive self-defense is debatable, let us pretend that it does exist for the sake of argument. Next, we need to figure out how to describe it, keeping in mind that making it too broad would go against both the letter and the spirit of the UN Charter. It could be argued that a country has the right to defend itself before an armed attack happens. This is better called proactive self-defense. A lot of people who support this idea point of view to the famous Caroline event in 1837. In this case, British troops in Canada attacked the American ship Caroline before they were even spotted.
People from the United States who felt bad for the Canadian rebels fighting against British rule used this ship to give them weapons. This event led to what is now known as the Caroline theory for the use of power over time. A state would have to show that it needed to use pre-emptive self-defense “instantly,” “overwhelmingly,” and “leaving no choice of means and no moment of deliberation.” Also, the right amount of force should be used. To put it another way, you could only legally defend yourself with force before an armed attack happened. You could not use force to stop an attack that was already happening.
The Caroline Doctrine and the Origins of Preemptive Force
However, people don’t agree on what “imminent” means. Milanovic says that the first meaning of “imminent” is a limited one that has to do with time. To put it another way, an “imminent” threat is close in time, or just around the corner. The second word is more general, like when someone says an attack might happen someday. If you let a state use preemptive self-defense based on the broad meaning of “imminent,” you’d be letting powerful states move against other states without any reason.
This would be an open invitation to armed attack, which goes against the very point of the UN Charter’s ban on the use of force. This broad meaning also doesn’t fit with the Caroline doctrine, which strongly discourages pre-emptive self-defense using words like “instant,” “overwhelming,” and “leaving no room for deliberation.” In short, there is a lot of evidence for a limited understanding of the word “imminent.”
Is a Nuclear Program Enough to Justify an Attack?
Israel must show that an attack from Iran was imminent, which means that an attack was about to happen, for its case for pre-emptive self-defense to be taken seriously when it comes to its use of force. Suppose you say that Israel acted in preemptive self-defense because Iran is getting closer to getting nuclear weapons, which could be an existential danger to Israel. In that case, you are using a broader definition of “imminent” that is not supported by international law.
Why Upholding International Law Still Matters Today
Some people might say this argument doesn’t make sense in a world where people don’t really follow international law. International law hasn’t stopped wars since the UN Charter was signed eighty years ago. However, international law is still the best way to tell if what a country does is legal. It is the only way that international law can hold state power responsible. Because of this, it is very important to use and defend international law when it is seriously broken by governments that think they can get away with it.
This article was written by Prabhash Ranjan and originally published in The Hindu on June 19, 2025, under the title “The Legality of Israeli Actions Under International Law.” All legal interpretations and views belong to the original author.