A/76/136 taken as a countermeasure such actions would be permitted as they would be in response to a violation of international law. In order to take countermeasures in response to a malicious cyber operation violating international law, the operation in question must have been attributed to a state. Right to self-defence In accordance with Article 51 of the UN Charter, states have the right for selfdefence in the case of an armed attack. In order to assess if a cyber operation reaches the threshold of the use of force or an armed attack based on Article 2(4) or 51 of the UN Charter, we must consider the scale and effects of the operation. If the effects of a cyber operation are comparable to a kinetic attack, it could constitute an armed attack. In such a situation, the injured state has the right to self-defence considering all applicable restrictions of the UN Charter and customary international law, such as proportionality and necessity. In its response to an armed attack by cyber means, the injured state is not necessarily limited to taking measures by cyber means – all means remain reserved to states in order to respond to an armed attack in a manner that is proportionate and in accordance with other provisions of international law. Estonia believes that cyber operations that cause injury or death to persons, damage or destruction could amount to an armed attack under the UN Charter. IV. Conclusions International law remains essential to relations between states for setting clear boundaries on what is and is not acceptable behaviour in cyberspace. Alongside other elements of the cyber stability framework, international law provides overarching guidance as to states’ international rights and obligations applicable to cyberspace. A clear need for deepening the understanding on how international law applies to cyberspace has been noted during discussions between states. We welcome the publication of expert and national views and work done by states as well as other stakeholders, including academia and relevant organisations. 51 Estonia is looking forward to further constructive exchanges of views, including under the auspices of the UN, on how international law applies to state use of ICTs. The UN is an inclusive and necessary format to enable substantive discussions on responsible state behaviour in cyberspace. States should also engage with all stakeholders, including the private sector, civil society and academia, to discuss international law issues. One possible and helpful avenue for further awareness raising on how existing international law applies in cyberspace could be as part of a permanent Programme of Action (PoA) under the auspices of the UN First Committee. __________________ 51 30/142 For example, the work done by the International Committee of the Red Cross on the application of international humanitarian law (IHL) to cyber operations during armed conflicts is commendable and can help with further study on how IHL principles apply in cyberspace. 21-09670