Related Rule
Spain
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section B. Avoidance or minimization of incidental damage
Spain’s LOAC Manual (1996) states: “The commander shall consider all precautions in order to avoid and, at least, to minimize civilian casualties and damage to civilian objects.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, División de Operaciones, 18 March 1996, Vol. I, § 10.8.d.(2).
Spain’s LOAC Manual (2007) states: “All feasible precautions must be taken to protect civilians and civilian property when carrying out attacks on military objectives.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 2.3.b.(2).
The manual further states: “The parties to the conflict must attempt to minimize the number of civilian casualties and damage to civilian property that military operations may cause.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 3.1.d.(4).
Spain’s Royal Ordinances for the Armed Forces (2009) states: “In the conduct of any operation, [members of the armed forces] must take into account the principle of distinction … in order to … avoid, as feasible, incidental loss of life, suffering, physical and material damage that may affect [the civilian population]”. 
Spain, Royal Ordinances for the Armed Forces, 2009, Article 111.