During the night of March 7, Russian forces carried out a concerted bombing campaign against Ukraine's energy facilities. The acts were widely condemned by the international community, including U.S. President Donald Trump, who wrote on social media that he was "strongly considering large scale sanctions" based on the attack and urged both parties to the negotiating table. At the same time, Kremlin spokesperson Dmitry Peskov stated that Ukraine's energy infrastructure is a legitimate target because it is "linked with Ukraine's military industrial complex and weapons production." Trump was right to call out Russia's attack and threaten sanctions, for several reasons. First, in diplomatic terms it created at least a slight veneer of even-handedness after his dressing down of Ukrainian President Volodymyr Zelenskyy at the White House last week, as well as his seeming alignment with Russian President Vladimir Putin in what is clearly a war of aggression in which Putin has committed the majority of war crimes. But second, international law demands calling out this particular conduct as worthy of reproach, because contrary to what Peskov claimed, a country's energy infrastructure does not become a legitimate military target just because it supports both civilian and military uses. International humanitarian law draws a clear distinction between civilian objects such as schools and hospitals, and military objectives that are meant to make an "effective contribution to military action." While the law is ambiguous in situations where a civilian object is being used in such a way as to make a direct military contribution to war, even then targeting of that object is subject to the principle of proportionality, by which harm to civilians must be weighed against military necessity. Moreover, targeting civilian objects for the purpose of terrorizing civilians is a war crime. While an argument could be made that attacks on energy infrastructure that result in power outages for a limited period of time are not comparable to collateral damage from kinetic attacks, this is clearly not the case during winter, when civilians are heavily dependent on that infrastructure for indoor heating. Moreover, such arguments generally don't take into account the knock-on effects of such strikes for the civilian population, such as the health implications of household refrigerators, municipal water sanitation systems and hospital medical equipment all losing access to power. In short, even if the language of humanitarian law makes occasional exceptions for military necessity that clearly outweighs the harm to civilians, such cases are rare. And those loopholes do not easily cover the kind of massive attacks on civilian infrastructure carried out by Russia, which would appear to instead be calculated to "spread terror among the civilian population." These rules were developed after World War II, when entire cities were burned to the ground based on the logic that they contained factories used to build munitions, thereby making them and all the civilians in them a military target. But as the postwar push to expand international humanitarian law recognized, if the fact that a civilian mobilization or infrastructure also supports a war effort transforms it into a target, the military-civilian distinction itself begins to break down. Rather, the International Committee of the Red Cross has postulated a more specific standard on the definition of "direct participation in hostilities" as applied to civilians, in which the burden of proof is on belligerents to prove beyond a doubt that any such instance meets that standard. When in doubt, under Article 52(3) of Additional Protocol 1 to the Geneva Convention, an object shall be assumed to be of a civilian character. The argument that "dual use" infrastructure constitutes a legitimate military target is often used as justification by states claiming the legal right to engage in such attacks. It's worth underscoring...