This week marks the 80th anniversary of the the United Nations General Assembly (UNGA), and world leaders have gathered in New York for the occasion. But amid mounting geopolitical tensions, rising climate change and increased challenges to the global rules-based order, the mood is not exactly celebratory. Instead, it would appear that the United Nations is being challenged like never before. One major reason is the split in the Security Council over Israel's war in Gaza and Russia's invasion of Ukraine. Its peacekeeping missions have also drawn criticism, particularly in Africa. And last year, a group of climate policy experts, including former UN climate chief Christiana Figueres, former UN Secretary-General Ban Ki-moon, and the prominent climate scientist Johan Rockstrom, called the COP climate summits "no longer fit for purpose." But Secretary-General Antonio Guterres stresses the importance of the United Nations to tackle global issues. "No country can stop a pandemic alone. No army can halt rising temperatures," he said on Tuesday while addressing the UN General Assembly.