The United Nations (UN) has long served as a forum for international diplomacy and collective action, but in an increasingly multipolar world and with the United States adopting a more isolationist stance under President Donald Trump’s second term, its effectiveness and relevance are under scrutiny. Here we assess the current role of the UN and its agencies, the consequences of reduced US engagement, and the challenges ahead, particularly in light of the upcoming selection of a new Secretary-General in 2026.
Trump’s Attitude Towards the UN: First and Second Term
During his first term, President Trump expressed open scepticism toward the UN, viewing it as bureaucratic, ineffective, and often opposed to US interests. His administration withdrew from several UN agencies, most notably the World Health Organization (WHO) in 2020, citing its alleged mishandling of the COVID-19 pandemic and undue influence from China.
Though the Biden administration later reversed this decision, Trump’s second term has seen a reversion to Trump's previous stance, with a second withdrawal from WHO in early 2025. This move, while largely symbolic, reflects broader disengagement from multilateral institutions.
Beyond the WHO, Trump has been critical of UN peacekeeping operations, calling for a reduction in US financial contributions, which historically have been the highest among member states. His administration has also questioned the utility of UN human rights mechanisms, withdrawing from the UN Human Rights Council in his first term and refusing to reengage in his second.
However the Trump administration does not seem to consider the UN entirely irrelevant. On 25 February 2025 the United States opposed (and hence effectively vetoed) a UK-France drafted UN Security Council resolution condemning Russia's role in the second invasion of Ukraine, and supported (and had passed) a second Security Council resolution calling for a ceasefire in Ukraine with the support of Russia. France and the United Kingdom had called for amendments to that resolution criticising Russia, which the United States vetoed and therefore the United Kingdom and France abstained from supporting the resolution. This was particularly surprising for the United Kingdom, which generally always votes with the US in the UN Security Council except on matters relating to the Israel / Palestine conflict. In such cases the United Kingdom typically abstains from voting with the United States on measures supporting Israel which refuse to condemn Israeli military actions causing excessive harm to Palestinian civilians or giving the impression that UN Security Council Resolution 242 of 1967, calling for Israeli withdrawal from the Gaza Strip and the West Bank, is diluted or undermined.
Cooperation between the US and Russia in the Security Council is rare, and is presumably part of a broader US initiative to mediate a ceasefire in Ukraine, something which the United States under her current leadership involves avoiding aggravating Russia with inflamatory statements and actively engaging with Russian diplomacy where points of agreement can be reached. The history of the UN Security Council and UN General Assembly (an inferior body within the UN governance architecture in which each member state has one vote but whose decisions are generally regarded as non-binding in the face of inconsistent UN Security Council resolutions) is replete with US-Soviet and US-Russia disagreements. These have been vocal, as for example when Soviet Premier Nikita Khruschev pounded his shoe on the desk at a meeting of the UN General Assembly on 12 October 1960 in disagreement at one of the speeches being made.
Implications of US Withdrawal from UN Institutions
The consequences of Trump’s isolationist approach are profound. Financially, the UN depends on the United States, which has historically contributed around 22% of its regular budget and over a quarter of peacekeeping funds. A reduction or withdrawal of these funds weakens the organisation’s capacity to respond to crises, from humanitarian disasters to conflict resolution efforts.
Moreover, Trump’s actions may embolden other nations to deprioritise or disengage from the UN. If the US reduces its role in multilateral diplomacy, China and Russia may seek to fill the vacuum, further shifting the ideological balance of the organisation in favour of non-democratic states. This could particularly impact issues such as global human rights norms, climate initiatives, and development aid, all issues about which President Trump has expressed scepticism. His defunding of USAID (the United States Agency for International Development, the development arm of the US federal government) and his withdrawal from the Paris Agreement on Climate Change in 2017 and again in 2025 (President Biden had reinstated the US in this agreement during his tenure between the two Trump administrations), which followed his pattern towards the World Health Organization, is indicative of his lack of interest in multilateral initiatives in these fields.
The Future of Multilateralism in a New Cold War
With tensions between Europe and Russia escalating, and the US showing reduced enthusiasm for NATO and other multilateral engagements, the UN could serve as a critical venue for diplomatic engagement. However without active US participation, its ability to serve as an effective arbitrator may be weakened. US Secretary of State Marco Rubio’s recent refusal to attend a G7 meeting in South Africa over concerns about China’s influence suggests a broader trend of US skepticism towards multilateralism. This trend raises questions about whether the UN can function effectively without American leadership, especially in addressing security concerns posed by Russia.
The Appointment of the Next UN Secretary-General in 2026
As the UN approaches the end of António Guterres’s second term in 2026 (he is prohibitied from holding a third term), the selection of his successor presents a crucial test for the institution. The process, while semi-transparent in 2016, remains subject to the influence of the P-5 nations (the US, UK, France, Russia, and China), all of whom hold an effective veto over the appointment. Trump may prefer a more opaque, backroom approach, potentially negotiating a candidate directly with Vladimir Putin, a move that would likely be met with resistance from the European powers and China.
Given Trump’s previous disdain for globalist institutions, he may favour a candidate who shares his scepticism of the UN’s traditional role or who is perceived as weak enough to limit its influence. Alternatively, he may simply neglect the process altogether, further marginalising the institution.
The UN’s Enduring Relevance and Potential for Reform
Despite its challenges, the UN remains a crucial platform for global governance. The Security Council, for all its dysfunction, still provides a venue where major powers can engage diplomatically, particularly in times of heightened geopolitical tensions.
Reforms are necessary to restore the UN’s credibility, particularly in reducing corruption and inefficiency. While the organisation currently appears impotent in addressing pressing global crises, institutional changes—such as modifying the veto power, increasing transparency in leadership selection, and streamlining bureaucratic structures—could make it more effective. However it is hard to see any of the P-5 member states agreeing to modify the veto power. At the current time, the P-5 member states represent three Great Powers (the US, Russia and China), a proxy (France) for a fourth Great Power (the European Union), and a bridge between the United States and the European Union (the United Kingdom). This is unlikely to change, as is the system of leadership selection which is likely to become more opaque, not less so. However streamlining bureaucratic structures might be something the P-5 could agree upon, provided that Russia and China are involved in such as a way as not to decrease their current increasing influence in the UN structures.
Conclusion - is there a future for multilateralism?
The UN’s future hinges on its ability to adapt to a world where US engagement is no longer guaranteed. If Trump continues to undermine the institution, its role in international affairs may diminish further, allowing other powers to shape its agenda. However, the enduring need for a global forum to address security, human rights, and development challenges suggests that, despite its flaws, the UN is unlikely to become entirely irrelevant. Instead, it must evolve to function effectively in a new multi-polar geopolitical era.