The primary factor leading to the establishment of the United Nations (UN) was the need for a cooperative global framework to prevent further conflicts and promote peace following World War II. Founded in 1945, the UN aimed to foster international collaboration and dialogue to address pressing global issues, including human rights, economic development, and social progress. The organization emerged from the lessons learned in World War I and the failure of the League of Nations, with member states recognizing that coordinated efforts were essential for maintaining peace and security in an increasingly interconnected world.