Related Rule
Switzerland
Practice Relating to Rule 12. Definition of Indiscriminate Attacks
Section B. Attacks which cannot be directed at a specific military objective
Switzerland’s ABC of International Humanitarian Law (2009) states: “The principle of distinction imposes limits on means and methods of warfare: any Weapon or strategy that cannot be directed exclusively at a specific military objective is prohibited.” 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, p. 17.