The great statesmanship and leadership that the United States showed during and after World War II is well known. America was the world's preeminent political, economic, and military power, and instead of using its position to penalise the losers and demand reparations, it helped plan and found multilateral global-governance institutions that would give all countries a seat at the table.
Under this new international order, postwar reconstruction and economic development was to be financed through the World Bank, while the international trading system was to be underpinned by the rule of law through the General Agreement on Tariffs and Trade and its successor, the World Trade Organization (WTO). The International Monetary Fund (IMF) was charged with ensuring global financial stability, and organisations such as the United Nations and Nato offered frameworks for addressing geopolitical tensions.
This rules-based world maintained peace and boosted prosperity. These achievements were all the result of multilateralism. To be sure, the US was and still is the de facto leader of this global order. But since it accounts for less than 5% of the world's population and only about one-fifth of global GDP, it is not large enough simply to dictate matters to everyone else. Instead, it relies on support from its allies to advance its goals and interests on the world stage.