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Spain
Practice Relating to Rule 37. Open Towns and Non-Defended Localities
Section C. Attacks on open towns and non-defended localities
Spain’s LOAC Manual (1996) prohibits attacks against open towns and non-defended localities. 
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, § 4.5.b.(3)(b).
The manual further states that “launching an attack against … non-defended localities” constitutes a war crime. 
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, § 11.8.b.(1).
Spain’s LOAC Manual (2007) prohibits attacks against open towns and non-defended localities. 
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, § 4.5.b.(3).(b).
Spain’s Penal Code (1995) provides for the punishment of “anyone who, in the event of armed conflict, should … knowingly violate the protection due to … undefended areas … which are duly identified with signs or the appropriate distinctive signals”. 
Spain, Penal Code, 1995, Article 612(1).