Règle correspondante
Switzerland
Practice Relating to Rule 43. Application of General Principles on the Conduct of Hostilities to the Natural Environment
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
14 Protected objects
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.
15 Methods of warfare
15.2 Prohibited methods of warfare
225 Indiscriminate attacks, i.e. attacks which cannot distinguish between protected persons/objects and military objectives, as well as attacks directed against protected persons/objects or acts of revenge are prohibited in any place and at any time.
17 Sanctions for violations of the international law of armed conflict
17.1 General provisions
237 The following in particular are criminal offences: … harmful acts against internationally protected persons and objects[.] 
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, 225 and 237.
Switzerland’s ABC of International Humanitarian Law (2009) states:
Civilian objects
International humanitarian law distinguishes between Civilian objects and Military objectives, prohibiting acts of violence against the former. Other provisions provide special protection for certain specific civilian objects, some of which are expected to bear distinctive signs: … the natural environment … . Civilian objects are all objects which are not military objectives.
Environment
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, pp. 12 and 20.