Fourth, if State B’s conduct violated international law, it would entitle State A to take countermeasures – acts which would ordinarily be unlawful – in response to State B’s wrongdoing. Countermeasures could be cyber in nature or taken through alternative means – such as temporarily not performing certain bilateral treaty obligations owed to State B. However, State A would need to ensure that such countermeasures:  were directed against State B  did not constitute a threat or use of force, violate fundamental human rights, humanitarian obligations prohibiting reprisals, or peremptory international legal norms  were reversible (as far as possible)  were proportionate to the injury suffered by State A, and  were intended to induce State B to comply with its international legal obligations. International law would not preclude State A from taking acts of retorsion, which are unfriendly acts that are not inconsistent with the international obligations of State A, including, for example, declaring diplomats from State B in State A persona non grata. 3 www.dfat.gov.au/cyberaffairs