The warnings started long before Donald Trump was even a presidential candidate. For at least a decade, a growing chorus of foreign policy experts had been pointing to signs that the international order was coming apart. Authoritarian powers were flouting long-accepted rules. Failed states were radiating threats. Economies were being disrupted by technology and globalization; political systems, by populism. Meanwhile, the gap in power and influence between the United States—the leader and guarantor of the existing order—and the rest of the world was closing.
Then came Trump’s election. To those already issuing such warnings, it sounded the death knell of the world as it was. Even many of those who had previously resisted pessimism suddenly came to agree. As they saw it, the U.S.-led order—the post–World War II system of norms, institutions, and partnerships that has helped manage disputes, mobilize action, and govern