The Security Council has a primary responsibility, under the UN Charter, for the maintenance of international peace and security.
When a complaint concerning a threat to peace is brought before it, the Council's first action is usually to recommend to the parties to try to reach agreement by peaceful means. In some cases, the Council itself undertakes investigation and mediation. It may appoint special representatives or request the Secretary-General to do so or to use his good offices. It may set forth principles for a peaceful settlement.
When a dispute leads to fighting, the Council's first concern is to bring it to an end as soon as possible. On many occasions, the Council has issued cease-fire directives which have been instrumental in preventing wider hostilities. It also sends United Nations peacekeeping forces to help reduce tensions in troubled areas, keep opposing forces apart and create conditions of calm in which peaceful settlements may be sought. The Council may decide on enforcement measures, economic sanctions (such as trade embargoes) or collective military action.
A Member State against which preventive or enforcement action has been taken by the Security Council may be suspended from the exercise of the rights and privileges of membership by the General Assembly on the recommendation of the Security Council. A Member State which has persistently violated the principles of the Charter may be expelled from the United Nations by the Assembly on the Council's recommendation.
A State which is a Member of the United Nations but not of the Security Council may participate, without a vote, in its discussions when the Council considers that that country's interests are affected.
Both Members of the United Nations and non-members, if they are parties to a dispute being considered by the Council, are invited to take part, without a vote, in the Council's discussions; the Council sets the conditions for participation by a non-member state.
Each Council member has one vote. Decisions on procedural matters are made by an affirmative vote of at least nine of the 15 members. Decisions onsubstantive matters require nine votes, including the concurring votes of all five permanent members. This is the rule of "great Power unanimity", often referred to as the "veto" power.
Under the Charter, all Members of the United Nations agree to accept and carry out the decisions of the Security Council. While other organs of the United Nations make recommendations to Governments, the Council alone has the power to take decisions which Member States are obligated under the Charter to carry out.
Under the Charter, the functions and powers of the Security Council are:
- to maintain international peace and security in accordance with the principles and purposes of the United Nations;
- to investigate any dispute or situation which might lead to international friction;
- to recommend methods of adjusting such disputes or the terms of settlement;
- to formulate plans for the establishment of a threat to peace or act of aggression and to recommend what action should be taken;
- to call on Members to apply economic sanctions and other measures not involving the use of force to prevent or stop aggression;
- to take military action against an aggressor;
- to recommend the admission of new Members and the terms on which States may become parties to the Statue of the International Court of Justice.
- to exercise the trusteeship functions of the United Nations in "strategic areas":
- to recommend to the General Assembly the appointment of the Secretary-General and, together with the Assembly, to elect the Judges of the International Court.