Règle correspondante
Practice Relating to Rule 70. Weapons of a Nature to Cause Superfluous Injury or Unnecessary Suffering
According to Indonesia’s Air Force Manual (1990), it is prohibited to employ weapons which cause unnecessary suffering. 
Indonesia, The Basics of International Humanitarian Law in Air Warfare, Indonesian Air Force, 1990, § 15(b)(5).
In its oral pleadings before the ICJ in the Nuclear Weapons case in 1995, Indonesia stated:
All international customary law and all treaties regulating the conduct of armed conflict among States are based on two fundamental principles, namely necessity and humanity … Actions which cause needless losses or suffering are prohibited. Furthermore, the employment of arms causing unnecessary suffering … is prohibited under the 1907 Hague Convention IV on Laws and Customs of Land Warfare. 
Indonesia, Oral pleadings before the ICJ, Nuclear Weapons case, 3 November 1995, Verbatim Record CR 95/25, p. 27.