A valuable primer on foreign policy: a primer that concerned citizens of all political persuasions—not to mention the president and his advisers—could benefit from reading. An examination of a world increasingly defined by disorder and a United States unable to shape the world in its image, from the president of the Council on Foreign Relations. Things fall apart; the center cannot hold. The rules, policies, and institutions that have guided the world since World War II have largely run their course. Respect for sovereignty alone cannot uphold order in an age defined by global challenges from terrorism and the spread of nuclear weapons to climate change and cyberspace. Meanwhile, great power rivalry is returning. Weak states pose problems just as confounding as strong ones. The United States remains the world's strongest country, but American foreign policy has at.