The
UNSC veto system was established in order to prohibit the UN from taking any future
action directly against its principal founding members. One of the lessons of the
League of Nations (1919–46) had been that
an international organization cannot work if all the major powers are not members. The expulsion of the
Soviet Union from the
League of Nations in December 1939, following its November 1939 attack on Finland soon after the outbreak of
World War II, was just one of many events in the League's long history of incomplete membership.