In 1945, the USA was powerful enough to bring everyone together and create a new global order. Today, over 80 years later, it is one of the primary forces destroying it.

This is not the first time that the USA has withdrawn from the international arena. It has stepped away from UN bodies before, including the Human Rights Council, the UN Educational, Scientific and Cultural Organization and the World Health Organization, and it never joined the International Criminal Court. But this time, the pullback is much deeper, wider and possibly permanent.

Now, the USA has pulled out of a wide range of major agreements and agencies, reduced funding and dismantled domestic structures that supported multilateral engagement, particularly USAID, which was an important vehicle for international development. It has also stepped back from development cooperation, human rights engagement and peace and security funding.

At the same time, it has not fully left the UN or rejected it. The USA is still a permanent Security Council member and is unlikely to give up that position. Although it risks losing its vote in the General Assembly if it fails to pay its dues, it will likely continue paying the bare minimum to stay inside the system.

This is not isolationism; it’s a strong form of unilateralism. The USA is still active globally, but it is far less willing to accept any multilateral constraints. In 2003, before invading Iraq, it sought backing in the Security Council and only acted alone when that support didn’t materialise. Now it acts first and justifies itself later, if at all. There is also a more open challenge to the sovereignty of countries including Greenland, Iran and Venezuela, and to the authority of the UN Charter. The scale and tone of what we are seeing now are unprecedented.

This is an existential moment, but not necessarily the end. The UN still performs three core functions.

The UN remains the only forum where major powers meet regularly through the Security Council. The five permanent members can discuss their differences and identify areas of cooperation. This has helped prevent direct conflict between great powers and, so far, there is no alternative structure that can replace that role.

At the same time, for most countries, particularly smaller states outside the G20 and other influential groups, the UN is still the main global platform where they can defend their interests. It provides development support, diplomatic space and peacekeeping they can’t access elsewhere.

Finally, we must recognise that the UN is the global norms creator in key frontier areas such as climate change, emerging technologies and global health. Even if some countries ignore these rules and the USA pulls back, many others remain committed. In some policy areas, we may see what could be described as a ‘UN minus one’ dynamic.

That said, the UN still needs to adapt. It can’t rely only on governments. It will have to work more closely with civil society and the private sector in more networked and flexible ways to fulfil its mission effectively.

There are several possible trajectories.

One possibility is that the system’s structure stays the same, but the leadership shifts from the USA to China. China is already the UN’s second-largest contributor and the largest peacekeeping contributor among the permanent Security Council members. If it assumes leadership, there would likely be continuity in peace and security, given its constant emphasis on respecting national sovereignty, and in trade and development, aligning with its Belt and Road Initiative. Human rights, however, would remain an area of concern.

But it isn’t clear China wants to assume full leadership. It is still focused on its domestic development and may not wish to carry the same global responsibility the USA once did. And even if it did, other powers, including middle powers and European states, might resist a UN dominated by China. So a simple leadership swap is unlikely.

Another possibility is that the world fragments into regional spheres of influence, with the USA focusing on the Americas, China on Asia and Russia on Europe, leaving Africa more uncertain. This would effectively mark the end of the UN-based order as we know it.

A third scenario is that middle powers work together to revive and reform multilateralism, ensuring it evolves in a way that works more broadly for all.

This interregnum is both a risk and an opportunity. The current system could collapse without replacement, but it could also be reshaped into a system that works for everyone.

In any scenario, civil society will be crucial. It can propose ideas about what a renewed multilateral system should look like, including possible UN Charter reforms. It can engage governments at the domestic level and push them to support cooperation rather than retreat. It can also help mobilise public support and resources. It is worth remembering that the 1948 Universal Declaration of Human Rights was significantly driven by civil society, including women, from all over the world.

At the same time, civil society must reflect on its structure. It has often been dominated by global north organisations. A legitimate future order will require stronger leadership and participation from the global south. Without that, any renewed multilateralism will struggle to gain credibility.