Related Rule
Netherlands
Practice Relating to Rule 21. Target Selection
The Military Manual (1993) of the Netherlands states: “When a choice is possible between several military objectives for obtaining a similar military advantage, the objective to be selected shall be that the attack on which may be expected to cause the least danger to civilian lives and to civilian objects.” 
Netherlands, Toepassing Humanitair Oorlogsrecht, Voorschift No. 27-412/1, Koninklijke Landmacht, Ministerie van Defensie, 1993, p. V-11.
The Military Manual (2005) of the Netherlands states:
When a choice is possible between various military objectives, to attain equal military advantage, the objective chosen should be that where the attack can be expected to pose least danger to the lives of the civilian population and civilian objects. 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, § 0544.
In its chapter on non-international armed conflict, the manual states: “Where operational choices exist, they [participants in an internal armed conflict] should select the target which poses the least danger to civilian lives and civilian objects.” 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, § 1046.
According to the Government of the Netherlands, commanders have to take all the precautionary measures required by Article 57 of the 1977 Additional Protocol I when carrying out an attack. 
Netherlands, Lower House of Parliament, Memorandum in response to the report on the ratification of the Additional Protocols, 1985–1986 Session, Doc. 18 277 (R 1247), No. 6, 16 December 1985, p. 7, § 17.