Related Rule
Ecuador
Practice Relating to Rule 158. Prosecution of War Crimes
Ecuador’s Naval Manual (1989) states: “In the event of a clearly established violation of the law of armed conflict, the aggrieved State may: … punish individual offenders either during the conflict or upon cessation of hostilities”. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 6.2.
The manual adds:
Belligerent States have the obligation, under international law, to punish their own nationals, whether members of the armed forces or civilians, who commit war crimes. International law also provides that belligerent States have the right to punish enemy armed forces personnel and enemy civilians who fall under their control for such offences. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 6.2.5.