Related Rule
Sweden
Practice Relating to Rule 7. The Principle of Distinction between Civilian Objects and Military Objectives
Section A. The principle of distinction
Sweden’s IHL Manual (1991) provides: “The parties shall always distinguish between … civilian property and military objectives.” 
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. 41.
The manual considers that the principle of distinction as stated in Article 48 of the 1977 Additional Protocol I is part of customary international law. 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section 2.2.3, p. 19.