United Nations System
There are 15 members of the Security Council, consisting of five veto-wielding permanent members (China, France, Russia, the United Kingdom, and the United States) and 10 elected non-permanent members with two-year terms. This basic structure is set out in Chapter V of the UN Charter. Security Council members must always be present at UN headquarters in New York so that the Security Council can meet at any time.
Military Staff Committee
Though the Military Staff Committee is referred to in the Charter prior to its formal establishment, including in Article 26 and earlier Articles in Chapter 7, it is actually established by Article 47, which defines the membership of the Committee as "the Chiefs of Staff of the permanent members of the Security Council or their representatives". It is also referred to in the first United Nations Security Council resolution. The MSC is the only subsidiary body of the Security Council named in the Charter, and by far the longest-standing subsidiary council of the UN. The MSC remains active in the UN as a cadre of military advisors to their government's diplomats and peacekeeping.