The year 2025 marks the 80th anniversary of the end of World War II and the founding of the United Nations. At the end of the war, the UN was born, a contemporary international order took shape, and the course of human history was forever altered. Over the past eight decades, the UN-centered system and the international law-based order have helped prevent a third world war, maintain relative global peace, and support post-war reconstruction and development.
Today, eight decades later, the world again stands at a crossroads. It is timely to reflect on how human society entered this era of cooperation, to examine the evolution of the international order, and to consider its future. These questions are central to reforming global governance and building a more just, secure future.
Before the UN’s creation, human civilization had never developed a fully global framework for peaceful coexistence. The 1648 Peace of Westphalia is often seen as the start of the modern state system, but for nearly 300 years thereafter, international relations remained dominated by colonialism, conquest, and the rule of force. The League of Nations, created after World War I, was humanity’s first attempt at a global peacekeeping institution. But its structure-hierarchical, exclusive, and unbalanced-proved unfit. It failed to stop the aggression of fascist powers, and its collapse paved the way for the deadliest war in human history.
The establishment of the UN in 1945 marked a significant milestone, opening a new historical stage in international relations and representing a major advance over previous world orders.
The United Nations, by contrast, was built on a radically different premise. The Charter, signed in San Francisco in 1945, codified key principles: the sovereign equality of states, non-interference, prohibition of force, and peaceful resolution of disputes. These were revolutionary commitments. For the first time, war was made legally impermissible. The Charter also affirmed the right to self-determination, which provided the foundation for decolonization across Africa, Asia, and Latin America. A new international system, with the UN at its core and a collective security mechanism centered on the Security Council, replaced the failed League. While the P5 veto introduced its own structural tensions, the system nonetheless enabled a long period of global stability and expansion.
Over the decades, this order has evolved. The UN had 51 members at its founding. Today, that number has grown to 193. The number of sovereign states has stabilized, and the rise of the Global South has become a defining feature of our century. Institutions such as the G77 now shape the multilateral agenda. International law has also matured-from custom to codification. More than 600 treaties now regulate nearly all areas of international interaction, from trade and transport to human rights and disarmament. Without these treaties, the world’s fragile legal order could not function.
The UN-centered system now includes six principal organs and 15 specialized agencies, from the WHO to the World Bank. Dozens of programs, funds, and commissions-UNICEF, UNDP, UNEP-now support the international development agenda. A comprehensive system of multilateralism has emerged to regulate nearly every sphere of human endeavor.
The international landscape, however, remains the most volatile part of this order. In the Cold War era, global politics were shaped by two blocs: the U.S.-led NATO alliance and the Soviet-led Warsaw Pact. The rise of the Non-Aligned Movement and the return of China to the UN in 1971 expanded the field of diplomacy and helped balance the bipolar struggle. After the Cold War, the U.S. briefly emerged as the sole superpower. But multipolarity has since returned, driven by the EU’s consolidation, China’s rise, and the growing assertiveness of the BRICS nations.
The 2008 global financial crisis marked a turning point. It exposed the limitations of a Western-centric governance model. The creation of the G20 Summit-bringing together both developed and developing countries-reflected a recognition that new voices must shape global rules. Since then, the Global South has grown more confident, and the geopolitical balance has shifted in subtle but important ways.
Yet the foundations of global governance have come under strain. Beginning in 2017, U.S. policy turned sharply inward. Under President Trump, the United States withdrew from multiple international agreements and institutions, including the Paris Agreement and the World Health Organization. Though some of these decisions were reversed under the Biden administration, a broader shift toward isolationism has continued. This year, the return of Trump to the White House brought a renewed retreat: re-imposing tariffs, rejecting global climate obligations, and expressing open hostility toward multilateralism. Such actions undermine the very order the U.S. once helped to create.
The challenges facing the international system are significant. Still, the answer is not dismantling the order-but reforming it. First, the UN system is not the property of any “founding states.” It is a global institution, belonging to all nations. Reform must aim not at replacement, but at revitalization through inclusive dialogue, shared responsibility, and cooperative problem-solving.
Second, while the UN has not fulfilled all its lofty ambitions, it has helped avert a third world war and enabled remarkable human progress. In 1945, the world population stood at 2.5 billion. Today, it exceeds 8 billion. Extreme poverty has fallen from 60 percent to under 10 percent. These gains are not incidental; they are rooted in the relative stability provided by international norms and institutions.
Third, many of today’s crises-climate change, nuclear proliferation, artificial intelligence-require global responses. The pillars of this system remain stable: a shared legal framework, a functioning multilateral infrastructure, and the principle of sovereign equality. The main variable is the behavior of major powers. The failure of consensus among the U.S., China, Russia, and the EU remains the greatest obstacle to a more effective UN.
Despite these obstacles, three positive trends suggest that multilateralism can endure. First, the world is becoming irreversibly multipolar. No single country can impose a unipolar model. The future will be shaped by four primary actors-China, the United States, Russia, and the European Union-and must accommodate the aspirations of the broader Global South. Second, despite current setbacks, economic globalization is irreversible. The global market is an enduring reality, and short-term protectionism will not erase decades of interconnectedness. Third, broad international support for multilateralism remains intact. Even as some countries retreat, most understand that global challenges require global solutions.
In this context, the international community must prioritize three key objectives. First, nuclear risk reduction. The five nuclear powers should reaffirm their January 2022 joint statement pledging to avoid nuclear war and prevent arms races. Second, collective climate action. G20 countries, especially those with high emissions, must accelerate implementation of the Paris Agreement and uphold the principle of “common but differentiated responsibilities.” Third, global AI governance. The UN’s “Pact for the Future” and the Global Digital Compact provide a starting point for ensuring that new technologies serve all of humanity, not just the few. Looking forward, the future of the international order depends on whether its defenders can work with enough unity and urgency to preserve and update its foundations. The 80th anniversary of the UN should serve not as a commemoration, but as a call to action. In September 2024, the first UN “Summit of the Future” set this process in motion. The Pact for the Future outlines a 19-point roadmap to reform the global governance system and strengthen the UN’s capacity. Its focus on inclusion, equity, and effectiveness is exactly what the moment demands.
To succeed, countries must reaffirm their commitment to the UN Charter, reject divisive blocs and exclusionary geopolitics, and champion universal values of justice, equality, and cooperation. China, as a major developing country, has a role to play-not only in advancing its own development, but in working with other Global South nations to defend multilateralism and build a more equitable world.
The international order born in 1945 was not perfect, but it was necessary-and remains so today. As the world faces a new era of strategic uncertainty, its repair and renewal is our shared responsibility. Reform must be steady, inclusive, and guided by a clear recognition: peace, justice, and global progress can only be secured when all nations share in shaping the rules that govern them.
The writer is former Under-Secretary-General of the United Nations.