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Spain
Practice Relating to Rule 10. Civilian Objects’ Loss of Protection from Attack
Section A. Civilian objects used for military purposes
Spain’s LOAC Manual (1996) states: “Civilian objects can become military objectives if by their location, purpose or use, they may assist the enemy, or if their capture, destruction or neutralization offers a definite military advantage.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 2.3.b.(1).
Spain’s LOAC Manual (2007) states:
A civilian object can become a military objective if, by its location, purpose or use, it makes an effective contribution to the enemy’s military action and if its total or partial destruction, capture or neutralization provides a definite military advantage. 
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.(1).