Since World War II, a formal system of alliances has been at the center of American foreign policy. But the world has changed so much in these decades, with new threats and new opportunities and with a dramatically different landscape in terms of the relative power of the United States and of other nations in world affairs. Looking forward, what should be the role of alliances in America's view of international relations? Guests: Kori Schake, Director of Foreign and Defense Policy Studies at the American Enterprise Institute Stephen Walt, Professor of International affairs at Harvard Rajan Menon, Chair Political Science at City College of New York.