Truman thought Stettinius was too soft on communism and had yielded too much to Moscow when he was Roosevelt 's advisor at Yalta . Truman had an old Senate friend in mind as a replacement , James F. Byrnes . Stettinius resigned as Secretary of State to take up the position of the first United States Ambassador to the United Nations . He chaired the United States delegation to the United Nations Conference on International Organization held in San Francisco from April 25 to June 26 , 1945 , which brought together delegates from 50 Allied nations to create the United Nations . Charles W. Yost , who had been Under Secretary of State Stettinius ' assistant in the State Department , was named Stettinius ' Executive Secretary at the United Nations Conference . Stettinius resigned in June 1946 , as he became critical of what he saw as Truman 's refusal to use the UN as a tool to resolve tensions with the Soviet Union
United Nations Conference on International Organization
United Nations Conference on International Organization
Edward Stettinius Jr.