Norma relacionada
Chad
Practice Relating to Rule 145. Reprisals
Section B. Reasonable notice and measure of last resort
Chad’s Instructor’s Manual (2006) states:
As reprisals violate the law of war in response to a breach of that law committed by the enemy, they must be the last resort in order to restore respect for the law of war. Consequently, to carry out reprisals, a formal prior warning must be issued. 
Chad, Droit international humanitaire, Manuel de l’instructeur en vigueur dans les forces armées et de sécurité, Ministère de la Défense, Présidence de la République, Etat-major des Armées, 2006, p. 93.