neutral States from the effects of such conflicts.109 Costa Rica understands the term “neutral State” as referring to any State which is not a party to an ongoing international armed conflict. 64. Parties to an international armed conflict are prohibited from carrying out cyber operations against and from cyber infrastructure located in the territory, and under the exclusive control of, neutral States.110 In Costa Rica’s perspective, they must also refrain from engaging in cyber operations that are reasonably expected to cause incidental harm to cyber infrastructure situated on the territory of neutral States. 65. Under the law of neutrality, a neutral State must not knowingly allow any use of cyber infrastructure located in its territory, or under its exclusive control, by parties to an international armed conflict for hostile purposes. This obligation is one of due diligence and is thus subject to the means reasonably available to the neutral State in question as well as its knowledge – actual or constructive – of such hostile uses of its cyber infrastructure. Conversely, the neutral State is not obliged to prevent parties to the conflict from using its networks solely for communication purposes. 109 See ICJ, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996, para. 89. Hague Convention V, Articles 1–3; Hague Convention XIII, Articles 1, 2, and 5; Tallinn Manual 2.0 (n 4), Rules 150–151. 110 18