Related Rule
Sweden
Practice Relating to Rule 12. Definition of Indiscriminate Attacks
Section B. Attacks which cannot be directed at a specific military objective
Sweden’s IHL Manual (1991) states: “According to Article 51, paragraph 4, [of the 1977 Additional Protocol I,] indiscriminate attacks are: … (b) those which employ a method or means which cannot be directed at a specific military objective”. 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section 3.2.1.5, p. 45