The founders created the United Nations to prevent a third world war, after two in just 30 years. Their vision endures. The UN may have had its successes and its failures in upholding the multinational approach to resolving conflict, but 75 years have passed since its inception without another global one. The General Assembly that began last month was a landmark event of the anniversary – a time for sober reflection and optimism. Sadly, it will be remembered, among statements from national leaders, for the contrast between just two of them that defined a dangerous fork in the road. The virtual addresses by the leaders of China and the United States could not have exposed more nakedly the growing tension between the UN concept of multilateralism and US unilateralism and isolationism. US President Donald Trump condemned China for “unleashing” the coronavirus and polluting the global environment. China’s President Xi Jinping said China would “firmly uphold” the multilateral system around the UN and, in a veiled swipe at the United States , rejected efforts by any country to “be the hegemon, bully or boss of the world”. The intensifying rivalry and friction show just how far China-US relations have fallen. On the UN stage it is difficult to reconcile with the darkest days of the Cold War, when it still served as a platform for the United States and the former Soviet Union to manage differences and reduce risks. Chinese President Xi Jinping hits out against hegemony and decoupling at UN The world is facing a challenge to peace and security unlike anything since the end of the World War II. The UN’s power for good comes from its core nations – the Security Council’s five permanent members, among whom the US and China are now pre-eminent. The UN charter may declare all countries equal but whether the organisation is effective basically depends on whether the five can build consensus. For Trump to use the UN as a platform for domestic electioneering, for what was seen as an effort to shift blame for more than 200,000 American Covid-19 deaths, and for attacking another UN member and its agencies as he chokes off funding, does not amount to an attack on China alone. It is not in line with a world order established after the Cold War. A new order that reflects American unilateralism could come at a steep price to prosperity and security. China has tried hard over the decades to maintain smooth relationships and gain support from many rank-and-file UN members. The principle that all members are equal, enshrined in the UN charter, remains paramount. Yet the reality is that some are more equal than others. The pressure is on China to show that it can pick up its share of responsibility for maintaining the world order that has been the foundation of global prosperity. Sooner or later, however, the UN must face the need for reform that reflects a wider basis for core consensus than a narrow post-war power structure.