During December 1941 , U.S. President Franklin D. Roosevelt devised the name " United Nations " for the Allies and proposed it to British Prime Minister Winston Churchill . He referred to the Big Three and China as a " trusteeship of the powerful " , and then later the " Four Policemen " . The Declaration by United Nations on 1 January 1942 was the basis of the modern United Nations ( UN ) . At the Potsdam Conference of July – August 1945 , Roosevelt 's successor , Harry S. Truman , proposed that the foreign ministers of China , France , the Soviet Union , the United Kingdom , and the United States " should draft the peace treaties and boundary settlements of Europe " , which led to the creation of the Council of Foreign Ministers of the " Big Five " , and soon thereafter the establishment of those states as the permanent members of the UNSC
Potsdam Conference
Potsdam Conference
Allies of World War II