This project is a comparative study of the dynamics of alliance maintenance in Europe and East Asia. The main case studies are Japan and Germany, supplemented by material from other regional alliance relationships, in particular France in Europe and South Korea in Asia. The central question it addresses is whether the US-led alliance system will be able to adapt itself to the changing security environment of the early twenty first century, or whether instead it is entering into a process of decay and possible dissolution. The study will focus in particular on the development of alliance relations in three key policy areas: territorial defense, extended deterrence and "out-of-area" contributions to international security. The analysis will be guided by a "thin Constructivist" theoretical perspective that focuses on the way in which elite and public discourse on intersect with concrete material forces (such as shifts in the balance of power or the development of social and economic interdependent relations with other countries) to shape policy outcomes. This Constructive perspective will be tested against, and supplemented by, Realist and Liberal IR theoretical perspectives that give primary causal weight to material factors such as military threat and economic dependency. The aim of this study is to contribute both to the International Relations literature on alliances, and to provide concrete suggestions to policy makers for improving alliance management.