Related Rule
Belgium
Practice Relating to Rule 15. The Principle of Precautions in Attack
Belgium’s Law of War Manual (1983) states: “When preparing attacks, care shall be taken to spare the civilian population and civilian objects.” 
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.
Belgium’s Law of War Manual (1983) provides: “Everything possible must be done to avoid incidental damage to civilian objects and loss of civilian life.” 
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.
Upon ratification of the 1977 Additional Protocol I, Belgium declared: “In view of the travaux préparatoires … ‘feasible precautions’ [are] those that can be taken in the circumstances prevailing at the moment, which include military considerations as much as humanitarian ones.” 
Belgium, Interpretative declarations made upon ratification of the 1977 Additional Protocol I, 20 May 1986, § 3.
Upon ratification of the 1977 Additional Protocol I, Belgium stated:
With respect to Part IV, Section I, of the Protocol, the Belgian Government wishes to emphasize that, whenever a military commander is required to take a decision affecting the protection of civilians or civilian objects or objects assimilated therewith, the only information on which that decision can possibly be taken is such relevant information as is then available and that it has been feasible from him to obtain for that purpose. 
Belgium, Interpretative declarations made upon ratification of the 1977 Additional Protocol I, 20 May 1986, § 3.