This chapter ties the book’s key findings and its main arguments together. It reminds the reader why the analysis in the book has not told the familiar tale of how the Berlin Wall came down and the Cold War ended, but the lesser known story of what happened during the period of systemic transition that began in the late 1980s and extended throughout the 1990s. The chapter articulates the book’s central argument that the ‘uncertainty doctrine’ has become firmly embedded in contemporary US defense policy. It draws together the wider lessons of the empirical analysis, and underscores that examining the processes surrounding critical turning points improves our understanding of the impact of the past on contemporary political developments and on future political possibilities. The chapter also considers the broader implications of the symbiotic relationship between changing security policy dynamics in the United States, political battles over defense priorities, the construction of security narratives, and our understanding of international security events.