The United Nations came into being in 1945following the devastation of the Second World Warwith one central mission: the maintenance of international peace and security. The UN does this by working to prevent conflict; helping parties in conflict make peace; peacekeeping; and creating the conditions to allow peace to hold and flourish. These activities often overlap and should reinforce one anotherto be effective. The UN Security Council has the primary responsibility for international peace and security. The General Assembly and the Secretary-General play majorimportantand complementary rolesalong with other UN offices and bodies.

One of the purposes of the United Nationsas stated in its Charteris "to achieve international co-operation in solving international problems of an economicsocialculturalor humanitarian character."  The UN first did this in the aftermath of the Second World War on the devastated continent of Europewhich it helped to rebuild.  The Organization is now relied upon by the international community to coordinate humanitarian relief operations due to natural and man-made disasters in areas beyond the relief capacity of national authorities alone.

The UN Charterin its Preambleset an objective: "to establish conditions under which justice and respect for the obligations arising from treaties and other sources of international law can be maintained."  Ever sincethe development ofand respect for international law has been a key part of the work of the Organization.  This work is carried out in many ways - by courtstribunalsmultilateral treaties - and by the Security Councilwhich can approve peacekeeping missionsimpose sanctionsor authorize the use of force when there is a threat to international peace and securityif it deems this necessary.  These powers are given to it by the UN Charterwhich is considered an international treaty.  As suchit is an instrument of international lawand UN Member States are bound by it.  The UN Charter codifies the major principles of international relationsfrom sovereign equality of States to the prohibition of the use of force in international relations.