The contemporary world confronts an enormous cyber threat. The U.S. intelligence community rates this threat higher than global terrorism. It warns of the severity of the damage a cyber attack could produce. Yet there is no consensus among scholars and decision makers on how to characterize 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 defense apply to this phenomenon. Principles of cyber defense and cyber offense 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 current cyber realities, applying insights from technological revolutions in previous eras.