A key figure in the establishment of the United Nations after World War II was Harry S. Truman, the 33rd President of the United States. He played a pivotal role in advocating for the formation of the UN to foster international cooperation and prevent future conflicts. Truman emphasized the need for a multilateral organization that could address global challenges, promote peace, and uphold human rights. His endorsement helped shape the UN's foundational principles and structure, laying the groundwork for its ongoing efforts in diplomacy, humanitarian aid, and maintaining international security.