Cyber aggression – be it espionage, sabotage or even warfare – among state actors is an increasing threat to international security and stability. Due to a lack of commonly accepted international rules or norms in the cyber security area, individual states are looking for the best way to deal with the threat.
One of the most effective methods in this regard is to deter cyber threats, preferably before the actual aggression starts or escalates. One potential foreign policy instrument that might be considered useful for cyber deterrence is the concept of signalling: informing any state that is conducting or sponsoring cyber aggression that this (hidden) activity is being monitored and that it may be met with retaliation.
Signalling might be an effective instrument to change the cost-benefit calculations of states engaging in or sponsoring cyber aggression activities. While especially cyber espionage and cyber sabotage are currently considered to be cheap, almost non-risk activities, the instrument of signalling may make them less anonymous and risk-free. Yet, the effectiveness of the instrument is difficult to measure.