The world has changed. Over the past decade, we have witnessed a distinct shift toward a renewed competition between the great powers. The bipolar struggle between the U.S. and China is the new Great Game of the 21st century.  Because both sides have nuclear weapons, we can expect leaders in Washington and Beijing to be reluctant to engage in behavior that might raise the risk of actual war. And we can be thankful that at least one key lesson came out of the Cold War: that neither side c