Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
Peru’s IHL and Human Rights Manual (2010) states:
IHL imposes on States the obligation to search for and punish all persons who have committed grave breaches [of IHL], irrespective of the nationality of the perpetrator or the place where they committed the crime. This obligation stems from the principle called UNIVERSAL JURISDICTION … , and includes the obligation to prosecute them or to extradite them. This obligation falls on all States affected by the commission of the crime.