The problem of change has preoccupied Russian thinkers for nearly several centuries. Experiencing change around them, they have tried to characterize it and analyze its sources. The concept of defensive innovation holds that a country may initiate reforms in order to remove or reduce a threat posed by another country. While the threat may be military in nature, it may also be cultural-ideological, demographic, or economic. The problem of change in Russia and the USSR assumes great importance in part because so many have felt that genuine change there is at best incomplete and at worst nonexistent. The process of that transformation can be divided into an almost limitless number of phases. A pre-industrial phase extended from the formation of the Muscovite state in the fifteenth century to the third quarter of the nineteenth century. The role of individual Russian and Soviet leaders in promoting change has been particularly emphasized in the West.