Related Rule
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section D. Information required for deciding upon precautions in attack
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.