The massing of Russian troops on the Ukrainian border is raising the specter of war between two countries that share a complex history of ethnic, linguistic, and political conflict and coexistence. Seven years after annexing Crimea and instigating a separatist revolt in eastern Ukraine, Russian president Vladimir Putin may be gambling that he can easily annex further territory -- or he might be bluffing about war to win concessions elsewhere. Whatever Mr. Putin's motivation, the possible incursion is exposing the failure of NATO's post-Cold War eastward expansion. In this episode, the Quincy Institute's Anatol Lieven discusses the deep historical roots of the Russia-Ukraine dispute -- a history lost on U.S. military analysts who advocated pushing NATO into Russia's historic backyard.