Соответствующая норма
Practice Relating to Rule 145. Reprisals
Section B. Reasonable notice and measure of last resort
Ecuador’s Naval Manual (1989) provides:
To be valid, a reprisal action must conform to the following criteria:
3. When circumstances permit, reprisal must be preceded by a demand for redress by the enemy of his unlawful acts.
5. Reprisal must only be used as a last resort when other enforcement measures have failed or would be of no avail. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, §