القاعدة ذات الصلة
Peru
Practice Relating to Rule 19. Control during the Execution of Attacks
Peru’s IHL Manual (2004) states:
There is … an obligation to suspend or cancel an attack if it becomes obvious that the target is not a military objective or is specifically protected or if the attack is likely to cause collateral damage which would be excessive in relation to the military advantage anticipated (rule of proportionality). This obligation is binding not only on those who give orders, but also on those who carry them out. 
Peru, Manual de Derecho Internacional Humanitario para las Fuerzas Armadas, Resolución Ministerial Nº 1394-2004-DE/CCFFAA/CDIH-FFAA, Lima, 1 December 2004, § 29.e; see also § 29.u.
The manual also states that those responsible for planning or deciding upon attacks must “cancel, suspend or adapt a planned attack if it becomes obvious that the incidental civilian damage is likely to be out of proportion to the specific gain from the attack (principle of proportionality)”. 
Peru, Manual de Derecho Internacional Humanitario para las Fuerzas Armadas, Resolución Ministerial Nº 1394-2004-DE/CCFFAA/CDIH-FFAA, Lima, 1 December 2004, § 29.b.(3).
Peru’s IHL and Human Rights Manual (2010) states: “The attack must be cancelled or suspended if it becomes clear that the objective or target is not a military one. In any case, the rule of proportionality must be respected.” 
Peru, Manual de Derecho Internacional Humanitario y Derechos Humanos para las Fuerzas Armadas, Resolución Ministerial No. 049-2010/DE/VPD, Lima, 21 May 2010, § 30(u), p. 254.
The manual also states:
(b) Those who plan or decide upon attacks must:
(3) Cancel, interrupt or modify an attack if it is considered likely that its collateral effects would be excessive to the anticipated military advantage (principle of proportionality). 
Peru, Manual de Derecho Internacional Humanitario y Derechos Humanos para las Fuerzas Armadas, Resolución Ministerial No. 049-2010/DE/VPD, Lima, 21 May 2010, § 30(b)(3), p. 242.