Nov 9, 2009, marked the 20th anniversary of the fall of the Berlin Wall, effectively marking the end of the Cold War. The collapse of the Berlin Wall, however, unleashed an incomplete process of integration and political transformation and left a band of states on Russia's Western periphery without a clear political future or clear foreign policy attachment. This band of states includes Ukraine, Georgia, Moldova, and Belarus. This article focuses on the changing security dynamics in Central Europe and the Western periphery of the post-Soviet space. The first section examines Russia's resurgence and the challenges it poses. The second section focuses on Ukraine's transition, while the third section discusses the impact of Russia's resurgence on Central and Eastern Europe. The fourth section examines the increasing cooperation between Russia and Germany. The fifth section analyzes the changing context of NATO enlargement. The final section discusses the implications of these trends for US policy.