Règle correspondante
United States of America
Practice Relating to Rule 54. Attacks against Objects Indispensable to the Survival of the Civilian Population
Section C. Attacks in case of military necessity
In 1973, a Deputy Legal Adviser of the US Department of State declared: “The generally accepted rule today is that crops and food supplies may be destroyed … if their destruction is required by military necessity and is not disproportionate to the military advantage gained.” 
United States, Address by George H. Aldrich, Deputy Legal Adviser of the Department of State, 13 April 1973, reprinted in Arthur W. Rovine, Digest of United States Practice in International Law, 1973, Department of State Publication 8756, Washington, D.C., 1974, pp. 503–504.
According to the Report on US Practice, the opinio juris of the United States recognizes the legality of attacks against objects indispensable to the survival of the civilian population when required by military necessity. 
Report on US Practice, 1997, Chapter 4.1.