Related Rule
Islamic Republic of Iran
Practice Relating to Rule 43. Application of General Principles on the Conduct of Hostilities to the Natural Environment
In 1991, during a debate in the Sixth Committee of the UN General Assembly on protection of the environment in armed conflict, the Islamic Republic of Iran stated:
Referring to the law of armed conflict, … both customary law and treaty law prohibited belligerent parties from inflicting either direct or indirect damage on the environment.
The principle of proportionality, which was enshrined in customary law, set important limits on warfare whereby damage not necessary to the achievement of a definite military advantage was prohibited. Another principle of customary law, whereby military operations not directed against military targets were prohibited, had been incorporated in the preamble of the 1868 Declaration of St. Petersburg to the effect of prohibiting the use of certain practices in wartime and in article 35.1 of [the 1977 Additional Protocol I]. Lastly, the [1907 Hague Regulations] prohibited the destruction of non-military enemy property unless imperatively demanded by the necessities of war … The Fourth Geneva Convention contained two provisions intended to ensure indirect protection of the environment in the context of protecting property rights in occupied territories. Thus, for example, an occupying Power which destroyed industrial installations in an occupied territory, causing damage to the environment, would be in violation of the Fourth Geneva Convention unless such destruction was justified by military necessity. If such destruction was extensive, it constituted a grave breach of the Convention and even a war crime. 
Islamic Republic of Iran, Statement before the Sixth Committee of the UN General Assembly, UN Doc. A/C.6/46/SR.18, 22 October 1991, §§ 27–28.
In its oral pleadings before the ICJ in the Nuclear Weapons case in 1995, the Islamic Republic of Iran argued:
As far as the law of armed conflict is concerned, both the customary rules and the provisions of treaty law prohibit belligerent parties, directly or indirectly, from inflicting unnecessary damage on the environment. Parties to the armed conflict are obliged, in accordance with well-established rules of customary law pertaining to armed conflict, to protect the environment in time of armed conflict. 
Islamic Republic of Iran, Oral pleadings before the ICJ, Nuclear Weapons case, 6 November 1995, Verbatim Record CR 95/26, p. 34, § 59.