Graham Allison, director, Belfer Center for Science and International Affairs at Harvard University
Cheng Li, senior fellow, Brookings Institution
Ashley Tellis, senior associate, Carnegie Endowment for International Peace
For decades, the U.S. and U.S.S.R. were locked in a checkmate that brought the countries to the brink of nuclear war. Now, a new multipolar landscape exists where at least nine countries have nuclear weapons and China is projected to become the world's largest economy.