Related Rule
Australia
Practice Relating to Rule 14. Proportionality in Attack
Section B. Determination of the anticipated military advantage
Australia’s Defence Force Manual (1994) refers to the declaration made by Australia upon ratification of the 1977 Additional Protocol I to the effect that references to military advantage in Articles 51(5)(b) and 57 of the Protocol mean “the advantage anticipated from the attack as a whole and not only from isolated or particular parts of the attack” and that “military advantage involves a number of considerations, including the security of the attacking forces”. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 510 and 511.
Australia’s LOAC Manual (2006) states:
5.10 … In relation to G. P. I [1977 Additional Protocol I], Australia has made a declaration to the effect that the Australian Government’s understanding is that references to military advantage in Articles 51(5)(b) and 57 mean:
the advantage anticipated from the attack as a whole and not only from isolated or particular parts of the attack.
5.11 In addition, the declaration makes it clear that military advantage involves a number of considerations, including the security of attacking forces … 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 5.10–5.11.
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 stated that references to “military advantage” were intended to mean “the advantage anticipated from the attack considered as a whole and not only from isolated or particular parts of that attack” and maintained that the term “military advantage” involved a number of considerations, including the security of the attacking forces. Australia also stated that the expression “concrete and direct military advantage anticipated” meant “a bona fide expectation that the attack will make a relevant and proportional contribution to the objective of the military attack involved”. 
Australia, Declarations made upon ratification of the 1977 Additional Protocol I, 21 June 1991, § 4.