Related Rule
United States of America
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section C. Feasibility of precautions in attack
At the CDDH, the United States stated:
The word “feasible” when used in draft Protocol I, for example in Articles 50 and 51 [57 and 58], refers to that which is practicable or practically possible, taking into account all circumstances at the time, including those relevant to the success of military operations. 
United States, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.42, 27 May 1977, p. 241.