Ashton Carter has an unusual background for a secretary of defense. Before assuming the United States’ top military post in February, he studied medieval history and particle physics as an undergraduate at Yale, got a Ph.D. in physics as a Rhodes scholar at Oxford, and taught international affairs at Harvard. He also served as an assistant secretary of defense in the Clinton administration and as an undersecretary and then the deputy secretary of defense under President Barack Obama. Since becoming secretary, Carter has displayed an unusual bluntness, openly criticizing Iraq’s military forces and talking tough to adversaries such as China and Russia. In his first full-length print interview since becoming secretary, Carter met with Foreign Affairs managing editor Jonathan Tepperman in his Pentagon office in early July.