Practice Relating to Rule 37. Open Towns and Non-Defended Localities
Section C. Attacks on open towns and non-defended localities
Ecuador’s Naval Manual (1989) states:
Belligerents are forbidden to bombard a city or town that is undefended and that is open to immediate entry by their own or allied forces. A city or town behind enemy lines is, by definition, neither undefended nor open, and military targets therein may be destroyed or bombarded.