In view of the challenges frequently encountered in providing assistance to civilians in opposition-held territories, consideration is sometimes given to cross-border relief operations. Such operations raise numerous legal questions, including whose consent is required; what constitutes arbitrary withholding of consent; what the consequences of withholding of consent are, both for those wishing to provide assistance and for the parties withholding consent; and what alternatives exist for providing assistance in such circumstances. Keywords: cross-border relief operations, consent of the affected state and the opposition, arbitrary withholding of consent, medical supplies and relief operations, starvation of the civilian population, unauthorised relief operations, state sovereignty, territorial integrity, non-interference, domestic law, assistance in the wrongful act of another state, circumstances precluding wrongfulness, counter-measures, necessity, indirect provision of assistance, binding Security Council decisions.