As this coming February will mark the third anniversary of Russia's invasion and occupation of Eastern Ukraine, there is already a clear and tangible impact upon the geopolitical challenges faced by the United States and her allies in Europe in terms of their roles in the international system. This week Departures with Robert Amsterdam is pleased to welcome back past guest Michael Kimmage, noted historian, former State Department official, and Associate Professor of History at the Catholic University of America in Washington DC. In this conversation we review his excellent new book, "Collisions: The Origins of the War in Ukraine and the New Global Instability," which critically examines the contributing causes to the outbreak of the war and measures the irrevocable ways in which the conflict has altered the course of US strategic engagement in the international sphere. In his book, Kimmage argues that the war has shattered three critical assumptions - that European peace was permanent, that Europe could continue to sustain this stability without heavy US involvement, and lastly, that Russia would be consigned to a peripheral role. With those assumptions now gone, Kimmage and host Robert Amsterdam discuss what we can expect next.