Related Rule
Practice Relating to Rule 1. The Principle of Distinction between Civilians and Combatants
Section B. Attacks against combatants
Sweden’s IHL Manual (1991) states: “A distinction shall always be made between persons participating in hostilities and who are thereby legitimate objectives, and members of the civilian population, who may not constitute objectives in warfare.” 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section, p. 40.