Related Rule
Australia
Practice Relating to Rule 7. The Principle of Distinction between Civilian Objects and Military Objectives
Section B. Attacks against military objectives
Australia’s Defence Force Manual (1994) provides:
210. … Military operations must only be conducted against enemy armed forces and military objects. Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack. The law of armed conflict therefore requires that belligerents maintain the clear distinction between armed forces and civilians taking no direct part in hostilities; that is, between combatants and non-combatants, and between objects that might legitimately be attacked and those protected from attack.
524. Only military objectives are legitimate objects of attack. During an armed conflict, and subject to the overriding considerations of proportionality and unnecessary suffering, the ADF [Australian Defence Force] may target any military objective.
531. There is a fundamental rule that parties to a conflict must direct their operations only against military objectives. …
913. The basic rule in respect of civilians which flows from this is that a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be carried out against military objectives. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 210, 524, 531 and 913.
Australia’s LOAC Manual (2006) states:
2.11 … Military operations must only be conducted against military objectives, including combatants.
5.26 Only military objectives are legitimate objects of attack. During an armed conflict, and subject to the overriding considerations of proportionality and unnecessary suffering, the ADF [Australian Defence Force] may target any military objective.
5.35 There is a fundamental rule that parties to a conflict must direct their operations only against military objectives.
9.13 … [A] distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 2.11, 5.26, 5.35 and 9.13; see also §§ 6.37 and 9.17.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Upon ratification of the 1977 Additional Protocol I, Australia declared:
It is the understanding of Australia that the first sentence of paragraph 2 of Article 52 is not intended to, nor does it, deal with the question of incidental or collateral damage resulting from an attack directed against a military objective. 
Australia, Declarations made upon ratification of the 1977 Additional Protocol I, 21 June 1991, § 5.