Related Rule
Practice Relating to Rule 21. Target Selection
Croatia’s LOAC Compendium (1991) gives the following instruction: “When your mission affords alternative objectives and targets, choose the course likely to cause minimum civilian casualties and damage.” 
Croatia, Compendium “Law of Armed Conflicts”, Republic of Croatia, Ministry of Defence, 1991, p. 43; see also p. 41.
Croatia’s Commanders’ Manual (1992) states: “Within tactically equivalent alternatives, the directions, objectives and targets of attack shall be chosen so as to cause the least civilian damage.” 
Croatia, Basic Rules of the Law of Armed Conflicts – Commanders’ Manual, Republic of Croatia, Ministry of Defence, 1992, § 50; see also § 66.