Соответствующая норма
Germany
Practice Relating to Rule 54. Attacks against Objects Indispensable to the Survival of the Civilian Population
Section C. Attacks in case of military necessity
Germany’s Military Manual (1992) provides: “Any deviations from this prohibition [attacking objects indispensable for the survival of the civilian population] shall be permissible only on friendly territory if required by imperative military necessity.” 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, § 463.