The future of world order

US President Donald Trump has cast serious doubts on the future of the postwar international order. In recent speeches and UN votes, his administration has sided with Russia, an aggressor that launched a war of conquest against its peaceful neighbor, Ukraine. The White House’s policy of imposing tariffs on trading partners has raised questions about long-standing alliances and the future of the global trading system, while its withdrawal from the Paris climate agreement and the World Health Organization has undercut cooperation on transnational threats.

The prospect of a wholly disengaged, self-focused US has troubling implications for world order. It is easy to imagine Russia taking advantage of the situation to try to dominate Europe through the exercise or threat of force. Europe will have to show greater unity and provide for its own defense, even if a US backstop will remain important. Likewise, it is easy to imagine China asserting itself more in Asia, where it openly seeks dominance over its neighbors. Those neighbors will surely have taken note.

In fact, all countries will be affected, because the relationships among states and other major transnational actors are interconnected. An international order rests on a stable distribution of power among states; norms that influence and legitimize conduct; and shared institutions. A given international order can evolve incrementally without leading to a clear paradigm shift. But if the preeminent power’s domestic politics change too radically, all bets are off.

Since relations among states naturally vary over time, order is a matter of degree. Before the modern state system, order was often imposed by force and conquest, taking the form of regional empires such as China and Rome (among many others). Variations in war and peace between powerful empires were more an issue of geography than of norms and institutions. Because they were contiguous, Rome and Parthia (the area around modern-day Iran) sometimes fought, whereas Rome, China and the Mesoamerican empires did not.

Empires themselves depended on both hard and soft power. China was held together by strong common norms, highly developed political institutions and mutual economic benefit. So was Rome, especially the Roman Republic. Post-Roman Europe had institutions and norms in the form of the papacy and dynastic monarchies, which meant that territories often changed governance through marriage and family alliances, regardless of the subject people’s wishes. Wars were often motivated by dynastic considerations, though the 16th and 17th centuries brought wars born of religious fervor and geopolitical ambition, owing to the rise of Protestantism, divisions within the Roman Catholic Church and increased interstate competition.

At the end of the 18th century, the French Revolution disrupted the monarchical norms and the traditional restraints that had long sustained the European balance of power. Although Napoleon’s pursuit of empire ultimately failed after his retreat from Moscow, his armies swept away many territorial boundaries and created new states, leading to the first deliberate efforts to create a modern state system, at the 1815 Congress of Vienna.

The post-Vienna “Concert of Europe” suffered a series of disruptions over the following decades, most notably in 1848, when nationalist revolutions swept the continent. Following these upheavals, Otto von Bismarck launched various wars to unite Germany, which assumed a powerful central position in the region, reflected in the 1878 Congress of Berlin. Through his alliance with Russia, Bismarck produced a stable order until Kaiser Wilhelm II fired him in 1890.

The prospect of a wholly disengaged, self-focused US has troubling implications for world order

Joseph S. Nye Jr.

Then came the First World War, which was followed by the Treaty of Versailles and the League of Nations, whose failure set the stage for the Second World War. The subsequent creation of the UN and the Bretton Woods institutions (the World Bank, the International Monetary Fund and the precursor to the World Trade Organization) marked the most important institution-building episode of the 20th century. Since the US was the dominant player, the post-1945 era became known as the “American Century.” The end of the Cold War in 1991 then produced a unipolar distribution of power, allowing for the creation or strengthening of institutions such as the WTO, the International Criminal Court and the Paris climate agreement.

Even before Trump, some analysts believed that this American order was coming to an end. The 21st century has brought another shift in the distribution of power, usually described as the rise (or, more accurately, the recovery) of Asia. While Asia had accounted for the largest share of the world economy in 1800, it fell behind after the Industrial Revolution in the West. And like other regions, it suffered from the new imperialism that Western military and communications technologies had made possible.

Now, Asia is returning to its status as the leading source of global economic output. But its recent gains have come more at the expense of Europe than the US. Rather than declining, the US still represents a quarter of global gross domestic product, as it did in the 1970s. While China has shrunk the US lead substantially, it has not surpassed the US economically, militarily or in terms of its alliances.

If the international order is eroding, America’s domestic politics are as much of a cause as China’s rise. The question is whether we are entering a totally new period of American decline, or whether the second Trump administration’s attacks on the American Century’s institutions and alliances will prove to be another cyclical dip. We may not know until 2029.

• Joseph S. Nye Jr., Professor Emeritus at Harvard University, is a former US assistant secretary of defense and author of the memoir “A Life in the American Century” (Polity Press, 2024). Copyright: Project Syndicate