When the responsibility of more than one state is engaged in relation to a wrongful cyber operation, the relevant states share responsibility for it. Shared responsibility can arise, for instance, when multiple states jointly conduct a cyber operation or when one state is involved in the cyber operation of another state (e.g., by providing assistance or exercising control). In view of the persistent difficulties associated with attribution of cyber conduct, shared responsibility can be a useful analytical framework to broaden the net of possible responsible states in relation to a cyber operation.