In mid-1944 , the delegations from the Allied " Big Four " , the Soviet Union , the UK , the US and China , met for the Dumbarton Oaks Conference in Washington , D.C. to negotiate the UN 's structure , and the composition of the UN Security Council quickly became the dominant issue . France , the Republic of China , the Soviet Union , the UK , and US were selected as permanent members of the Security Council ; the US attempted to add Brazil as a sixth member , but was opposed by the heads of the Soviet and British delegations . The most contentious issue at Dumbarton and in successive talks proved to be the veto rights of permanent members . The Soviet delegation argued that each nation should have an absolute veto that could block matters from even being discussed , while the British argued that nations should not be able to veto resolutions on disputes to which they were a party . At the Yalta Conference of February 1945 , the American , British , and Russian delegations agreed that each of the " Big Five " could veto any action by the council , but not procedural resolutions , meaning that the permanent members could not prevent debate on a resolution
Yalta Conference
Yalta Conference
United Nations Security Council