Under Donald Trump, however, U.S. foreign policy shows clear signs of significant departure. Support for alliances, embrace of free trade, concern over climate change, championing of democracy and human rights, American leadership per se—these and other fundamentals of American foreign policy have been questioned and, more than once, rejected. Trump is the first post–World War II American president to view the burdens of world leadership as outweighing the benefits. As a result, the United States has changed from the principal preserver of order to a principal disrupter.

This change has major implications. It will make it far more difficult to deal with the challenges posed by globalization, including climate change and nuclear proliferation, to regulate cyberspace on terms compatible with American interests, or to help relieve the plight of refugees on terms consistent with American values. It will make it more difficult to build frameworks that promote trade and investment and to ensure that the United States benefits from them.