Related Rule
Ecuador
Practice Relating to Rule 18. Assessment of the Effects of Attacks
Ecuador’s Naval Manual (1989) states:
Naval commanders must take all reasonable precautions … In each instance, the commander must determine whether incidental injuries and collateral damage would be excessive, on the basis of an honest and reasonable estimate of the facts available to him. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 8.1.2.1.