On 13 June 2025, the Israeli Defence Force launched a series of coordinated attacks against Iranian assets and military objectives under an operation codenamed Rising Lion. Although the operation’s stated primary target was Iran’s nuclear programme, the strikes hit conventional military sites as well as individual Iranian officials. Even as the Israel-Iran war escalates, questions of legality among other controversies regarding Israel’s conduct have arisen.
The legal conventions of war and aggression can be divided into three concepts, each tied to the individual phases of war - jus ad bellum governing the initiation of war, jus in bello constraining the means by which war is waged, and jus post bellum regulating the considerations for and after the termination of war.
Presuming that Israel has satisfied jus ad bellum requirements, this article will confine itself to jus in bello issues and adopt Michael Walzer’s traditional theory of just war in its legal assessment of Israel’s strikes specifically against individuals. Although revisionist views have emerged in more recent times, the traditional theory of just war remains the more entrenched and widely accepted criteria in State practice. As such, Walzer is a helpful starting point. Jus in bello, otherwise known as international humanitarian law (IHL), encompasses two principles: discrimination and proportionality. They are products of an attempt at a delicate balance between military necessity and humanitarian considerations.
Principle of Discrimination
We first turn to discrimination. The principle of discrimination confers civilians and non-combatants with immunity from direct attacks. However, these individuals lose their immunity once they take a direct part in hostilities. Prof. Michael Schmitt identifies three interpretive issues that arise from civilian immunity: (1) the definition of a civilian, (2) the scope of ‘direct participation in hostilities’, and (3) when does protection end? To answer the first, we adopt the International Committee of Red Cross’ negatively delimiting definition of a civilian as “all persons who are neither members of the armed forces of a party to the conflict nor participants in a levee en masse”. This leaves us with the second and third questions. While most would agree that direct participation should not be narrowly construed to acts involving violence against combatants, its scope is hotly contested. Prof. Michael Schmitt’s benefit-harm based approach is a well-reasoned framework. It argues that three “cumulative factors” need to be satisfied. The act must:
Be likely to adversely affect or enhance the military operations or capacity of a party to conflict
Be an integral part of the conduct that harms or benefits another militarily
Have a strong nexus with hostilities
The approach is deliberately broad enough that combat support activities would fall within the purview of direct participation. Examples of combat support include the collection of military intelligence, the maintenance of war equipment, and building of base fortifications. In other words, individuals are legitimate targets when they are engaged in being instruments of war. At this juncture, it is crucial to highlight two caveats. Firstly, protection is only suspended when individuals are in the midst of doing the act. Secondly, the proviso must preclude activities that overlap with human needs. This would, appropriately, exclude instances like food production, energy generation and facilitation of medical aid. These activities contribute to the war effort only because they are fundamentally human needs.
The Legality of Targeting Individuals
Having established that the scope of non-combatant immunity ends at the borders of being an instrument of war, we assess Israel’s efforts to intentionally kill top Iranian officials as part of Operation Rising Lion and in conjunction - Operation Narnia. Individuals like the Chief of Staff of Iranian Armed Forces and senior nuclear scientists were targeted and eliminated by Israel. Since military commanders are not civilians by definition, their killings were legally permissible in war.
The killing of nuclear scientists under Operation Narnia is considerably more problematic. A common-sense approach will suggest that these scientists are civilian employees of the government. Therefore, the legal question turns on whether they have taken a direct part in the hostilities and if so, whether their civilian immunity was suspended at the time of the attacks. Assuming Israeli claims that Iran’s extensive nuclear programme was reaching the scientific threshold for weaponisation is true, then the work of the nuclear scientists satisfies Schmitt’s benefit-harm framework. Their activity significantly enhances Iran’s military capacity by adding nuclear weapons to its arsenal and the scientists’ developmental work is integral to reaching the weaponisation threshold. On the basis of Iran’s consistent sabre-rattling rhetoric of using nuclear weapons to “annihilate” Israel, it is reasonable to suggest that the nuclear scientists’ actions have a strong nexus to Iran’s ongoing military hostilities. Of importance is the assumption that these scientists were themselves working on the development of nuclear weapon capabilities rather than simply nuclear energy.
Nevertheless, Israel’s killing of these scientists was illegal because they failed at the final step. That is, civilian immunity for these top scientists was not suspended at the time of their killing. The facts reported by The Times of Israel state that the ten Iranian nuclear scientists were killed “while they were sleeping in their beds”. Prof. Brian Orend reminds that “targeting [individuals] while at home in residential areas would be illegitimate” because they were not actively engaged in the act that made them, for a time being, equivalent to combatants in legal status. At the moment that these Iranian nuclear scientists were asleep in their bed, they were as Walzer emphatically describes it, just “a man”.
Principle of Proportionality
We conclude briefly with a comment on the principle of proportionality. Proportionality seeks to minimise collateral damage to civilians when military objectives are attacked. It nonetheless permits unintended harm to civilians so long as the means used are proportionate to the expected military utility of the target. Walzer explains that the death or injury to civilians must fulfill all four criteria: (1) unintentional, (2) proportional to desired objective, (3) not a direct means to the military effect intended, and (4) due care must be exercised to minimise harm to civilians even if combatants face an increased risk.
Given that the Iranian scientists had civilian immunity at the time of their killings, it falls to the proportionality question. From the outset, their deaths were disproportionate because their deaths were intended. They necessarily fail too at hurdles three and four.
Singapore’s Diplomatic Position
Since the escalation of the Israeli-Iran conflict, Singapore has openly urged for peace in the Middle East. Although its public statemeents were brief, it reveals Singapore’s staunch determination to advocate for the rule of law which has always coursed through the veins of its foreign policy.
Conclusion
Even though Operation Rising Lion marks a dangerous escalation of military conflict in the Middle East, it was, at the very least, legally justified in areas like the killing of military commanders and the striking of nuclear sites. However, the deaths of the Iranian scientists could not be lawful even under the extraordinary legal conventions of war.
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Schmitt M, ‘Deconstructing Direct Participation in Hostilities: The Constitutive Elements’ (2010) 42 New York University Journal of International Law and Politics
Shany Y and Cohen A, ‘A New War or a New Stage in an Ongoing War – Observations on June 13 Israeli Attack against Iran’ (Just Security, 15 June 2025) <https://www.justsecurity.org/114641/israel-iran-un-charter-jus-ad-bellum/> accessed 2025
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