The United States can no longer reign supreme as the world’s sole superpower, says Zbigniew Brzezinski, President Jimmy Carter’s National Security adviser and a prolific foreign affairs scholar. “The era of global supremacy by a major power . . . is over,” he tells Yahoo. “The world is now much more diversified. There is now the new East in Asia. There is now a globally, politically awakened population.” But that doesn’t mean the demise of the United States, as long as we’re willing to make some changes, Brzezinski, says. “We have to accustomize ourselves to that world. If we want...