Ian Bremmer is the president of Eurasia Group and GZERO Media and author of "Us vs. Them: The Failure of Globalism."
In the days and weeks that followed the Sept. 11, 2001, terrorist attacks on New York and Washington, a consensus emerged about how best to prevent future such catastrophes. Ungoverned expanses of territory, political officials warned us, become breeding and training grounds for extremists. In this way, some countries that produce little of value can begin to export violence, refugees and turmoil.