<h1>Nighttime attacks on power and heating risk unlawful strikes and war crimes under Article 54(1) AP I; intent and proportionality</h1> Nighttime strikes damaged power and heating systems in two Russian cities near the border, causing blackouts, fires at utility sites and disruption to tens of thousands of households. Under international humanitarian law, deliberate attacks on civilian infrastructure essential for survival can amount to unlawful attacks or war crimes if carried out intentionally or with reckless disregard for civilian harm; parties must distinguish between military and civilian objects and take feasible precautions. Attribution, intent, proportionality and corroborating evidence will be central to any criminal or state-responsibility inquiries, and affected states may seek investigations, reparations or emergency protective measures.