Related Rule
Switzerland
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section B. Avoidance or minimization of incidental damage
Switzerland’s Basic Military Manual (1987) states: “During every attack, commanding officers at the battalion or group level, and those of higher ranks, shall see to it that the civilian population … does not suffer any damage.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 29(1).
Switzerland’s ABC of International Humanitarian Law (2009) states:
Conduct of hostilities
Not all Means and methods of warfare are allowed in an Armed conflict. International humanitarian law stipulates the military operations, tactics and weapons that are permissible. The two generally accepted principles of Distinction and Proportionality are the basis for a number of specific rules such as the prohibition of direct attacks on the civilian population or on Civilian objects, the prohibition of indiscriminate attacks and the obligation to adopt precautionary measures (Precaution) so as to avoid or limit casualties among Civilians and damage to civilian objects to the greatest possible extent. 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, pp. 13–14.
In 2010, in its objection to the reservation by the United States to the 1980 Protocol III to the Convention on Certain Conventional Weapons, Switzerland stated:
Upon depositing the instrument of ratification of Protocol III to the Convention on Certain Conventional Weapons on 21 January 2009, the United States of America made a reservation with reference to paragraphs 2 and 3 of article 2 of the said Protocol. According to the reservation, the United States
“reserve[s] the right to use incendiary weapons against military objectives located in concentrations of civilians where it is judged that such use would cause fewer casualties and/or less collateral damage than alternative weapons, but in so doing will take all feasible precautions with a view to limiting the incendiary effects to the military objective and to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects”.
Switzerland appreciates the willingness expressed by the United States to take all feasible precautions to protect the civilian population and individual civilians not directly participating in hostilities. Switzerland considers that these measures are in keeping with the fundamental principle of distinction under international humanitarian law, a principle that is enshrined, in particular, in articles 57 (2) (ii) and 57 (4) of the first 1977 Protocol Additional to the Geneva Conventions of 1949. These provisions require each party to a conflict to “take all reasonable precautions to avoid losses of civilian lives and damage to civilian objects”.
Nonetheless, Switzerland considers that the reservation made by the United States is incompatible with the object and purpose of Protocol III, and therefore it objects to the reservation for the following reasons: …
Switzerland considers that this objection does not constitute an obstacle to the entry into force of Protocol III as between Switzerland and the United States of America. 
Switzerland, Objection to the Reservation by the United States of America to the 1980 Protocol III to the Convention on Certain Conventional Weapons, 2 February 2010.
In 2012, Switzerland’s Federal Department of Foreign Affairs issued a press release entitled “Appeal by the Swiss authorities for compliance with international humanitarian law in Syria”, which stated:
International humanitarian law is applicable to non-international armed conflict.
4. International humanitarian law is applicable in non-international armed conflicts. All parties to the conflict are therefore obliged to respect its rules in all circumstances, including the rules protecting persons who are [not] or are no [longer] participating in the hostilities, as well as the rules relative to the means and methods of warfare. …
Appeal to respect international rules
7. [Switzerland] recalls that in the conduct of military operations, all feasible precautions must be taken with a view to avoid incidental loss of civilian life[,] injury to civilians and damage to civilian objects and collateral damage to civilian property. All parties are subject to the obligation to respect the principles of distinction, proportionality and precaution. 
Switzerland, Federal Department of Foreign Affairs, “Appeal by the Swiss authorities for compliance with international humanitarian law in Syria”, Press Release, 15 November 2012.