prohibited to interfere with their functioning using cyber means, irrespective of whether doing so would amount to an attack as understood under IHL. In Costa Rica’s view, this obligation also encompasses a prohibition against deleting or tampering with medical data (a category that includes data necessary for the proper use of medical equipment, tracking medical supplies, and personal medical data required for patient treatment). 60. Under IHL, personnel and objects engaged in or used for humanitarian relief operations must be respected and protected by the parties to the conflict at all times.104 In Costa Rica’s view, this obligation entails a prohibition against attacking or otherwise harming humanitarian relief personnel and objects, an obligation to take feasible measures to protect them against harm, and a prohibition against using cyber operations to interfere with the impartial efforts to provide humanitarian relief, even if this interference would not rise to the level of attack. Costa Rica understands the obligation to respect and protect relief personnel and objects as also covering the associated data. 61. Under IHL, it is prohibited to attack, destroy, remove or render useless objects indispensable to the survival of the population, including when using cyber operations.105 The protection under this rule extends to the ICT equipment and the data needed to operate such objects. Thus, for example, a cyber operation against food production systems, drinking water installations, or wastewater management systems would be a violation of IHL even if it did not reach the threshold of attack under IHL.106 Duty to respect and ensure respect for IHL 62. All States and parties to armed conflicts have an overarching obligation to respect and ensure respect for IHL in all circumstances, including with regard to cyber operations during armed conflicts.107 As noted in para. 40, this general duty entails that certain additional measures with relevance to the use of ICTs must be taken already in peacetime to ensure respect for IHL in the event an armed conflict occurs. In addition, States must investigate and prosecute persons suspected of having committed war crimes, including through the use of ICTs during armed conflict.108 States must also refrain from transferring cyber weapons, means and methods of warfare where there is a clear risk that these would be used to commit IHL violations. Neutrality 63. The law of neutrality is applicable to cyber operations carried out during an international armed conflict, and it protects the populations and the cyber infrastructure in 104 Geneva Convention IV, Articles 59, 70(4), and 71(2); ICRC Customary International Humanitarian Law Study, Rules 31–32. 105 Additional Protocol I, Article 54; ICRC, Customary International Humanitarian Law Study, Rule 54. 106 Tallinn Manual 2.0 (n 4), Rule 141, para. 6, at 533. 107 Geneva Conventions, common Article 1; Additional Protocol I, Article 1; ICRC, Customary International Humanitarian Law Study, Rules 139 and 144. 108 Geneva Conventions I–IV, Articles 49/50/129/146; Additional Protocol I, Article 85; ICRC, Customary International Humanitarian Law Study, Rule 158. 17