Related Rule
Belgium
Practice Relating to Rule 54. Attacks against Objects Indispensable to the Survival of the Civilian Population
Section B. Attacks against objects used to sustain or support the adverse party
Belgium’s Law of War Manual (1983) states that there is a prohibition to attack, destroy or render useless objects indispensable to the survival of the civilian population, “except if these objects are used by the adversary solely for the sustenance of its armed forces, or if that is not the case, if they serve nonetheless in direct support of military action”. 
Belgium, Droit Pénal et Disciplinaire Militaire et Droit de la Guerre, Deuxième Partie, Droit de la Guerre, Ecole Royale Militaire, par J. Maes, Chargé de cours, Avocat-général près la Cour Militaire, D/1983/1187/029, 1983, p. 28.