Related Rule
France
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section C. Feasibility of precautions in attack
Upon ratification of the 1977 Additional Protocol I, France stated that it considered that the term “feasible” as used in the Protocol meant “that which can be realized or which is possible in practice, taking into account all circumstances ruling at the time, including humanitarian and military considerations”. 
France, Reservations and declarations made upon ratification of the 1977 Additional Protocol I, 11 April 2001, § 3.