United Nations Security Council
The Security Council consists of fifteen members. The great powers that were the victors of World War II—the Soviet Union (now represented by Russia), the United Kingdom, France, China, and the United States—serve as the body's five permanent members. These permanent members can veto any substantive Security Council resolution, including those on the admission of new member states or candidates for Secretary-General. The Security Council also has 10 non-permanent members, elected on a regional basis to serve two-year terms. The body's presidency rotates monthly among its members.
Charter of the United Nations
2. The non-permanent members of the Security Council shall be elected for a term of two years. In the first election of the non-permanent members after the increase of the membership of the Security Council from eleven to fifteen, two of the four additional members shall be chosen for a term of one year. A retiring member shall not be eligible for immediate re-election.