In the days and even hours leading up to the ceasefire with Iran, US President Donald Trump and his administration had been issuing increasingly escalatory threats against the Islamic Republic — from sending it back to the “stone age” and bombing its vital power plants to “ending” it as a civilisation. Any of these threats, if carried out, would have qualified as a war crime at the very least, according to international law.But while the reasoning for the tag may be clear for certain actions — bombing civilians, for instance — it is less clear how blowing up power plants would qualify as a war crime.To understand this, one must first understand that a “war crime” is not just an informal classification but a definition codified in international law. It is also distinct from “crimes against humanity” and “genocide”. So, what exactly is a war crime? We explain.What are war crimes?War crimes are serious violations of humanitarian laws during a conflict. The definition originates in the 1949 Geneva Conventions and was established by the Rome Statute of the International Criminal Court (ICC) in 1998.The Geneva Conventions also give rise to international humanitarian law (IHL), the body of rules that governs how wars are fought. Both are parts of international law. The IHL lays down three basic principles: distinction, proportionality and precaution. The first principle calls for distinguishing civilians from belligerent forces. The second prohibits an excessively forceful response to an attack. And the third requires the parties involved in the fighting to minimise harm to civilians.Also in Explained | Iran-US ceasefire: What each side was fighting for, and what they have won or lostSo, while the IHL seeks to impose limits on the destruction and suffering caused by armed conflict, the Rome Statute sets out punishment for individuals (who can be held liable for the State’s actions) for breaking them.Story continues below this adThe Rome Statute gives the ICC jurisdiction over four similar but legally distinct crimes. These are “the crime of genocide”, “crimes against humanity”, “war crimes” and the “crime of aggression”.Article 6 of the Rome Statute defines “genocide” as acts aiming to destroy, in whole or in part, a national, ethnic, racial or religious group. Article 7, which covers crimes against humanity, defines it as acts such as murder or displacement that are part of a systematic attack against civilians.Article 8b defines the crime of aggression as the planning, preparation, initiation, or execution of an act of aggression.Story continues below this adAnd Article 8 deals with war crimes, laying out its definition as mentioned at the beginning of this section.The four differ from each other not only in scale of seriousness but also the situation. According to the statute, genocide and crimes against humanity can happen in peacetime or during the unilateral aggression of a military towards a group of unarmed people. On the other hand, war crimes, as the name suggests, occur during a domestic conflict or a war between two states.So, what would exactly qualify as a war crime? Here’s what the statute says.What qualifies as war crimes?The ICC’s “Elements of Crimes” framework defines dozens of acts as possible war crimes. These include wilful killings, torture, hostage-taking, and rape.Story continues below this adAlso part of the framework are acts that are relevant in the context of Trump’s threats: Attacking civilians and civilian objects — those that are not part of military objectives. Iran’s bridges and power plants, therefore, would form part of this category — unless they were being used for a military purpose. That did not seem to be the case.“Iranian power plants and other critical civilian infrastructure are protected from attacks by the law of war the United States helped craft after World War II. Such an object can lose its protection only if it is used for military purposes by the enemy and its destruction ‘offers a definite military advantage’. Even then, such an object can be attacked only if, after a case-by-case rigorous analysis, the ‘concrete and direct military advantage anticipated’ outweighs the civilian suffering that is expected to result,” wrote two former UK judge advocate general officers, Margaret Donovan and Rachel VanLandingham, on the website Just Security on Monday.More in Explained | After the ceasefire: The politics, geopolitics and challenges for peace in the Middle EastAccording to Erika Guevara-Rosas, Amnesty International’s Senior Director of Research, Advocacy, Policy and Campaigns, even in the limited cases that such infrastructure qualifies as a military target, a party still cannot attack power plants if this may cause disproportionate harm to civilians. “Given that such power plants are essential for meeting the basic needs and livelihoods of tens of millions of civilians, attacking them would be disproportionate and thus unlawful under international humanitarian law, and could amount to a war crime,” she said in a statement.“When power plants collapse, horrific consequences cascade instantly. Water pumping stations would stop functioning, clean water would become scarce, and preventable diseases would spread. Hospitals would lose electricity and fuel, forcing surgeries to be cancelled and life-support machines to shut down. Food production and distribution networks would collapse, deepening hunger and causing widespread food scarcity. Many businesses would also shut down with devastating economic consequences including mass unemployment,” Guevara-Rosas said.Story continues below this adAdditionally, even the US Department of Defense’s own Law of War Manual discourages attacks aimed solely at diminishing the morale of people.The IHL states that measures of intimidation or terrorism against the civilian population are prohibited, including acts or threats of violence, the primary purpose of which is to spread terror among the civilian population. When Trump threatened to end the Iranian civilisation, such an act would qualify not as war crime but a genocide.According to Agnès Callamard, Secretary General of Amnesty International: “…It may constitute a threat to commit genocide, a crime defined by the Genocide Convention and by the Rome Statute of the International Criminal Court as committing one or more defined acts ’with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such’.”