United Nations Security Council
Along with the five permanent members, the Security Council of the United Nations has temporary members that hold their seats on a rotating basis by geographic region. Non-permanent members may be involved in global security briefings. In its first two decades, the Security Council had six non-permanent members, the first of which were Australia, Brazil, Egypt, Mexico, the Netherlands, and Poland. In 1965, the number of non-permanent members was expanded to ten.
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.