Threat Status with Philip Zelikow: Is humanity on the edge of world war?

Wars are raging in the Mideast, Europe and Africa. Tensions are rising in Asia, and anti-U.S. power alignment is tightening among authoritarian China, Russia, Iran and North Korea. National Security Editor Guy Taylor sits down with historian and former diplomat Philip Zelikow at the Hoover Institution at Stanford University for a discussion on whether humanity is edging dangerously close to world war and what U.S. policy makers can learn about the current dynamics by examining those that resulted in global conflict during the last century.