While the General Assembly is charged with a wide array of responsibilities for facilitating international cooperation, the Security Council's primary responsibility under the United Nations Charter is the maintenance of international peace and security.
The Security Council has the authority to investigate any dispute which might escalate to cause international tension, to recommend action for mitigating such disputes, to recommend to the General Assembly the appointment of the Secretary-General and new member states, and, with the GA, to elect the judges of the International Court of Justice.
In addition, the Council is authorized by the Charter to call on United Nations members to apply economic sanctions and other measures not involving the use of force to prevent to stop aggression and, in certain cases, to authorize member states to take military action against an aggressor.
The Security Council meets year round, generally in New York, though on occasion it has convened in other locations. It is composed of representatives from 15 member nations. There are five permanent member nations of the Security Council and ten elected member nations that each serve two-year terms. The permanent members are China, France, the Russian Federation (formerly the USSR), the United Kingdom and the United States. The presidency of the Security Council rotates every month according to the English alphabetical listing of the 15 member nations. Each year the General Assembly elects five new members to replace the five nations whose terms expire every December 31.
Procedural votes in the Security Council require the approval of a simple majority of the members. Substantive decisions require the approval of nine members, including the concurring votes of all five permanent members. This permanent member unanimity requirement is often referred to as the veto power, though no such term actually exists in the UN charter.
It should be noted that this unanimity requirement can still be met if a permanent member voluntarily abstains from a vote; not all permanent members must vote yes, but no motion may pass if any permanent members vote no. Each permanent member of the Council has used this so-called veto power at least once.
The Security Council has three basic mechanisms for expressing its opinions. The first is a press release that only has the effect of transmitting the work of the Council to the media. The second is a Presidential Statement, issued at the discretion of the current President, which expresses the President's opinion on a matter before the Council. The third and most powerful option is a Security Council resolution.
The resolutions of the Security Council, unlike those of the General Assembly, are binding upon all UN member nations. In accepting the Charter, all nations agree to accept and carry out these decisions of the Security Council. If states are generally non-compliant with Security Council resolutions, the Council can ask the International Court of Justice for an advisory opinion or it can recommend the suspension of a nation's privileges.
When responding to a problem region somewhere in the world, the Council first tries to find a peaceful resolution to the situation. However, in cases where this proves ineffective or insufficient, the Council, with the permission of host countries, can authorize the deployment of troops from member nations to help enforce or maintain a brokered peace.
While the Security Council can authorize the deployment of troops, neither the Council nor the UN equips or provides the troops and member states cannot be forced to supply troops if they choose not to do so. The United Nations has no standing international police or military force or equipment to enforce the decisions of the Security Council. As a result, the success of authorized missions is contingent upon troop contributions from member states.
In addition to peacekeeping operations, the Security Council oversees the International Tribunal for the Former Yugoslavia and the Criminal Tribunal for Rwanda. These two international tribunals are distinct from the International Court of Justice and are designed to bring the instigators and perpetrators of violations of international human rights laws to justice. These two tribunals were independently convened and are not part of a permanent International Criminal Court, a body not yet in existence but toward which various parts of the UN are working.
Under the Charter, the functions and powers of the Security Council are as follows:
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 Statute 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.