Related Rule
Peru
Practice Relating to Rule 17. Choice of Means and Methods of Warfare
Peru’s IHL Manual (2004) defines the terms “means of warfare” and “methods of warfare” as:
Means of warfare: The weapons and weapon systems by means of which violence is exercised against the enemy.
Methods of warfare: The tactics or strategy used in hostilities to defeat the enemy by using available information on him together with weapons, movement and surprise. 
Peru, Manual de Derecho Internacional Humanitario para las Fuerzas Armadas, Resolución Ministerial Nº 1394-2004-DE/CCFFAA/CDIH-FFAA, Lima, 1 December 2004, Chapter 9, Glossary of Terms.
The manual also states:
Appropriate means of warfare must be chosen and used with a view to:
(a) preventing unnecessary civilian casualties and damage to civilian property;
(b) minimizing, at any event, the number of casualties and unavoidable damage. 
Peru, Manual de Derecho Internacional Humanitario para las Fuerzas Armadas, Resolución Ministerial Nº 1394-2004-DE/CCFFAA/CDIH-FFAA, Lima, 1 December 2004, § 27.b.
Peru’s IHL and Human Rights Manual (2010) states:
Appropriate means of combat must be chosen in order to:
(a) Prevent unnecessary civilian casualties and damage to civilian property.
(b) Minimize, at any event, the number of civilian casualties and unavoidable damage. 
Peru, Manual de Derecho Internacional Humanitario y Derechos Humanos para las Fuerzas Armadas, Resolución Ministerial No. 049-2010/DE/VPD, Lima, 21 May 2010, § 28(b), p. 237.
In its Glossary of Terms, the manual also states:
Means of warfare: The weapons and weapon systems by means of which violence is exercised against the enemy.
Methods of warfare: The tactics or strategy used in the conduct of hostilities to defeat the enemy by using available information on him, together with weapons, movement and surprise. 
Peru, Manual de Derecho Internacional Humanitario y Derechos Humanos para las Fuerzas Armadas, Resolución Ministerial No. 049-2010/DE/VPD, Lima, 21 May 2010, p. 409.