David E. Sanger discusses U.S. rivalry with the other two great nuclear powers—Xi Jinping’s China and Vladimir Putin’s Russia—the choices that lie ahead, and what is at stake for the United States and the world. This special event is being held to honor the memory of Leslie H. Gelb, CFR’s president from 1993 to 2003 and a dedicated member for forty-six years. Gelb modernized the institution to reflect the changing realities of the post-Cold War era, and was a passionate advocate of common sense and strategy in U.S. foreign policy.