This norm provides guidance on what may be expected to constitute appropriate State behaviour. The UK recognises the importance of States taking appropriate, reasonably available, and practicable steps within their capacities to address activities that are acknowledged to be harmful in order to enhance the stability of cyberspace in the interest of all States. But the fact that States have referred to this as a non-binding norm indicates that there is not yet State practice sufficient to establish a specific customary international law rule of ‘due diligence’ applicable to activities in cyberspace. 13. The term ‘attribution’ is used in relation to cyberspace in both a legal and non-legal sense. It is used in a legal sense to refer to identifying those who are responsible for an internationally wrongful act. It is also used in a non-legal sense to describe the identification of actors (including non-state actors) who have carried out cyber conduct which may be regarded as hostile or malicious but does not necessarily involve an internationally wrongful act. 14. For the UK, there are technical and diplomatic considerations in determining whether to attribute publicly such activities in cyberspace. The decision whether to make a public attribution statement is a matter of policy. Each case is considered on its merits. The UK will publicly attribute conduct in furtherance of its commitment to clarity and stability in cyberspace or where it is otherwise in its interests to do so. 15. Whatever the nature of the attribution, there is no general legal obligation requiring a State to publicly disclose any underlying information on which its decision to attribute conduct is based. COUNTERMEASURES 16. Resort may be had to countermeasures in response to an internationally wrongful act, in accordance with international law, in relation to States’ activities in cyberspace as in relation to their other activities. This includes both resorting to countermeasures against a State whose cyber activities constitute internationally wrongful acts and carrying out countermeasures by means of cyber operations. Countermeasures need not be symmetrical: where the internationally wrongful act is itself not a cyber activity, the response may nonetheless involve cyber-based countermeasures (and vice versa). 17. An injured State may only take countermeasures against a State which is responsible for an internationally wrongful act in order to induce that State to comply with its obligations. Any measures adopted must be commensurate with the injury suffered. They must be carried out in accordance with the conditions and restrictions established in international law and must in particular not contravene the prohibition on the threat or use of force, must be necessary and proportionate to the purpose of inducing the responsible State to comply with its obligations and must not contravene any other peremptory norm of international law. 5