Over the past several years, rising cyber power has comprehensively and profoundly affected international security. Key areas include military operations, terrorism, critical infrastructure, corporate security, individual privacy and financial security, and political processes. The burgeoning development of information technology did not always seem especially daunting from a strategic perspective. For instance, as recently as the Arab ‘spring’, which began less than a decade ago, social media seemed to power political liberalisation, casting the digital revolution as an engine of social progress. It may yet prove to be that, but for the time being less salutary aspects of the technological march have arguably overtaken the sunnier ones. The articles in this collection reflect this arc.