The story would repeat itself time and again: The policy elites believed the best way to protect U.S. interests was through a postwar Western order organized around free trade, institutions, and a U.S. military presence in Europe and Asia. They couldn’t drum up enough political support for the idea until they could sell it as a vital part of the struggle with the Soviets.

The policy of supporting the liberal international order enjoyed great success. Democracy spread. Economic growth brought hundreds of millions out of poverty. Dozens of countries joined old alliances and institutions, spreading democracy, human rights, and market economies in the process. It was good strategy, although the term liberal international order was hardly used during the Cold War. While G. John Ikenberry brought the term to prominence in the 1990s and 2000s in his scholarship about American postwar strategy, it did not appear in The New York Times until 2012. Western foreign-policy thinkers saw it as a way of preserving the institutional and alliance architecture created during the Cold War, while opening up the Western bloc of democracies so all nations could participate in a rules-based system if they so chose.

Yet the notion of a liberal international order never really resonated with voters. And its success arose from the fact that American power was unrivaled—a fact that would change.

Internationalists, myself included, argued that without U.S. leadership the world would become a more dangerous and more hostile place. This may be true, but it is a hard case to make. The United States has led for so long that many people are unaware of the costs. The 2003 invasion of Iraq and other strategic mistakes have undermined America’s credibility, not least with its own citizens. The successes are taken for granted. As my colleague Robert Kagan pointed out in his new book, The Jungle Grows Back, despite their significant differences, Barack Obama and Donald Trump both understood that the American people wanted to pull back, do less, and have other nations share more of the burden.

How Trump is ending the American era

It has now become clear that we are in the early stages of a dramatic change in world politics that necessitates a change in strategy. For several years now, geopolitical competition between the major powers has been intensifying. Russia became much more aggressive in Eastern Europe and the Middle East. China grew more assertive in East Asia. What we did not know, until very recently, was that this competition would also directly and negatively impact the lives of citizens in Western democracies.

Examples abound: Russia’s attack on American democracy. Cyberattacks on critical infrastructure, including the power grid. Chinese political interference, including pressure on American companies, especially in the media and social-media sector. The mass theft of intellectual property. The collection of private data by foreign powers. The strategic use of corruption to build networks of support. And backing for authoritarian movements in countries that were, until several years ago, stable democracies.