The contemporary world confronts an enormous cyber threat. Western intelligence communities rate this threat higher than global terrorism. They warn of the severity of the damage a cyberattack could produce. Yet there is no consensus among scholars and decision makers on how to characterise the strategic instability of cyber interactions or on what to do about it. The range of conceivable cyber conflict is poorly understood. It is unclear how conventional security mechanisms such as deterrence and collective defence apply. Principles of cyber defence and offence remain rudimentary. The growth of cyber arsenals, in short, is outpacing the design of doctrines to limit their risks. This presentation will review problems of strategic adaptation to cyber phenomena, applying insights from technological revolutions in previous eras.