Соответствующая норма
Practice Relating to Rule 45. Causing Serious Damage to the Natural Environment
Switzerland’s Basic Military Manual (1987) prohibits the employment of means of warfare likely to cause “serious and long-term damage to the natural environment”. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 17.
The manual further states: “During military operations, care must be taken to protect the environment against widespread, long-term and severe damage.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 25(3).
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
14.5 Natural environment
217 Care shall be taken in warfare to protect the natural environment against widespread, long-term and severe damage.
218 Methods and means of warfare that are intended or may be expected to cause such damage to the environment are prohibited. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance on the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, §§ 217–218.
In 1981, Switzerland’s Federal Council qualified Articles 35(3) and 55 of the 1977 Additional Protocol I as stating a “new prohibition”. 
Switzerland, Federal Council, Message concernant les Protocoles additionnels aux Conventions de Genève, 18 February 1981, p. 38, § 211.411.
Switzerland’s ABC of International Humanitarian Law (2009) states:
Attacks and combat methods that can cause widespread, long-term and severe damage to the natural environment are expressly prohibited by the First Additional Protocol to the Geneva Conventions. The general principles of Customary international law such as the principles of Distinction and Proportionality ensure protection of the environment. 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, p. 20.
In 2012, in a speech on the occasion of Public International Law Day, the head of Switzerland’s Federal Department of Foreign Affairs stated:
Today we have at our disposal a developed body of law whose aim, for above all humanitarian reasons, is to limit the effects of armed conflicts and to protect those who take no part in hostilities. That law, which also protects cultural property and the natural environment, let us not forget it, is international humanitarian law. …
International humanitarian law then seeks to limit the consequences of armed conflicts. … It also prohibits intentionally destroying the natural environment without which a society cannot develop. 
Switzerland, Speech by the head of the Federal Department of Foreign Affairs on the occasion of the Public International Law Day, 19 October 2012.