Since March, the Zaporizhzhia nuclear power plant in southern Ukraine has been under Russian occupation. Since late July, the largest nuclear plant in Europe has been shelled repeatedly, with Kyiv and Moscow blaming each other for the attacks. This has sparked fears of a nuclear disaster. Last week, the UN Security Council held an emergency meeting on the situation without getting any closer to a solution.

It is not the first time in this war that the question of nuclear safety and security has been raised. This is not only about the potential use of nuclear weapons — Russian President Vladimir Putin has openly expressed this thought — but also about nuclear power stations being used as military targets.

Geneva Conventions regulate conduct of war

What does international law say about this? The 1949 Geneva Convention and its subsequent Additional Protocols regulate the conduct of armed conflict and seek to limit its effects. Article 56 of the Additional Protocol (1) of 1977 pertains to the "Protection of works and installations containing dangerous forces" and explicitly mentions "dams, dykes and nuclear electrical generating stations."

Since the Russian Federation and Ukraine are both parties to the agreement and have not expressed reservations about the Additional Protocol (1), the regulations apply to both states.

And they are surprisingly detailed. In principle, according to paragraph 1, nuclear power plants "shall not be made the object of attack, even when these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population." Radioactivity is certainly what is meant here.

The issue here is one of the principles of international humanitarian law as consolidated by the Geneva Conventions: The difference between military and civilian targets. These provide for the "general protection of civilian objects, restricting attacks to military objectives."

Nuclear power stations are not off-limits

But paragraph 1 of the Additional Protocol (1) does not state that nuclear power plants are always off-limits, only to the extent that an attack "may cause the release of dangerous forces from the works or installations and consequent severe losses among the civilian population." In other words, if it is not expected to cause "severe losses among the civilian population," then it might be permitted under certain circumstances.

Paragraph 2 suggests that a nuclear power plant could become an objective "if it provides electric power in regular, significant and direct support of military operations and if such attack is the only feasible way to terminate such support […]"

However, this is of course a matter of interpretation. In times of war, almost all nuclear power plants will provide electricity to civilians as well as to the military. It is hard to separate the two. But does this entail a "significant and direct support of military operations?" Thus, it is up to the discretion of the observer to evaluate whether a nuclear power plant is a legitimate military target or not.

It is also difficult to prove that an attack is "the only feasible way to terminate" support for acts of war. A potential aggressor has to deliberate and observe the principle of proportionality: Does the military value clearly prevail? What impact would my actions have on the civilian population? And would there not be a less grave means of rendering a nuclear power plant inoperable? Such as destroying power lines so that electricity can no longer be supplied — without entailing the risk of causing radiation? That said, for a population in winter, a power supply disruption can also be grave.

Civilian population must be protected

But even if circumstances do justify an attack, the Additional Protocol states in paragraph 3 that in all cases "the civilian population […] shall remain entitled to all the protection accorded them by international law." A warring party would have to do everything possible to protect civilians from radiation, for example, by evacuating the surrounding areas before launching an attack on a plant.

Paragraph 5 is also relevant to Zaporizhzhya: "The Parties to the conflict shall endeavor to avoid locating any military objectives in the vicinity of the works or installations mentioned in paragraph 1." Ukraine accuses Russia of hunkering down at the power plant, effectively using it as a shield to avoid Ukrainian shelling. While Vladimir Rogov, a Russian-backed local official, claimed that Ukraine had launched artillery strikes using US-made howitzers near the power plant and in residential areas.

Qualifying the restrictions, however, the Additional Protocol also states: "Nevertheless, installations erected for the sole purpose of defending the protected works or installations from attack are permissible and shall not themselves be made the object of attack." Russia will surely depict its military as only acting defensively.

In conclusion: The states that have signed the Geneva Conventions and its Additional Protocols — and that includes Russia and Ukraine — have set a high bar for attacks on nuclear power plants. But they are not ruled out entirely, even if the circumstances, in which they are permitted, are very narrowly defined.

But in practice Article 56 of the Additional Protocol (1) is limited. It remains a matter of interpretation as to whether circumstances allow for a concrete case. Moreover, as a permanent member of the United Nations Security Council, Russia has a veto and can prevent any attempts by the body to sanction it for violating international law.

This article was originally written in German.