Related Rule
Ecuador
Practice Relating to Rule 14. Proportionality in Attack
Section A. General
Ecuador’s Naval Manual (1989) states: “Loss of civilian life, injury to civilians or damage to civilian objects, incidental to an attack upon a legitimate military objective, are not illegal. Such injury or collateral damage must not, however, be excessive in light of the military advantage anticipated by the attack.” 
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.
The manual further specifies: “A weapon is not indiscriminate simply because it may cause incidental or collateral civilian casualties, provided such casualties are not foreseeably excessive in light of the expected military advantage to be gained.” 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 9.1.2.