When Truman took office , several international organizations that were designed to help prevent future wars and international economic crises were in the process of being established . Chief among those organizations was the United Nations , an intergovernmental organization similar to the League of Nations that was designed to help ensure international cooperation . When Truman took office , delegates were about to meet at the United Nations Conference on International Organization in San Francisco . As a Wilsonian internationalist , Truman strongly supported the creation of the United Nations , and he signed United Nations Charter at the San Francisco Conference . Truman did not repeat Woodrow Wilson 's partisan attempt to ratify the Treaty of Versailles in 1919 , instead cooperating closely with Senator Arthur H. Vandenberg and other Republican leaders to ensure ratification . Cooperation with Vandenberg , a leading figure on the Senate Foreign Relations Committee , would be crucial for Truman 's foreign policy , especially after Republicans gained control of Congress in the 1946 elections . Construction of the United Nations headquarters in New York City was funded by the Rockefeller Foundation and completed in 1952
United Nations Conference on International Organization
United Nations Conference on International Organization
Presidency of Harry S. Truman