Related Rule
Belgium
Practice Relating to Rule 11. Indiscriminate Attacks
Belgium’s Law of War Manual (1983) provides: “Indiscriminate attacks are forbidden.” 
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. 27.
Belgium’s Law concerning the Repression of Grave Breaches of the Geneva Conventions and their Additional Protocols (1993), as amended in 1999, provides that it is a crime under international law to launch
an indiscriminate attack affecting the civilian population or civilian objects in the knowledge that such attack will cause loss of human life, injury to civilians or damage to civilian objects which would be excessive in relation to the concrete and direct military advantage anticipated, without prejudice to the criminal nature of an attack whose harmful effects, even where proportionate to the military advantage anticipated, would be inconsistent with the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience. 
Belgium, Law concerning the Repression of Grave Breaches of the Geneva Conventions and their Additional Protocols as amended, 1993, Article 1(3)(12).