When the United Nations was established in 1945, the Security Council was comprised of eleven members: five permanent and six non-permanent members. The five permanent seats were held by the United States, France, United Kingdom, Soviet Union, and China, while the remaining seats were designated as non-permanent and rotated among the other 46 Member States for two-year terms. As new Member States joined the Organisation, they expressed the need for equitable geographic representation in the Council and on 17 December 1963, the General Assembly approved amendments to Articles 23, 27 and 61 of the UN Charter to increase the number of members of the Security Council from eleven to fifteen and to increase from seven to nine the number of votes required for adoption of decisions by the Council. On 20 December 1965, the General Assembly adopted resolution 2101(XX), amending article 109 of the Charter; replacing the number of voting members from “seven” with “nine”.
On 1 February 1966, the Security Council meets for the first time in the history of the United Nations with an expanded membership of 15 and a more equitable representation of all the regions of the world.
In 1958, shortly after the launching of the first artificial satellite, the United Nations was concerned about the use of outer space and decided to establish the Committee on the Peaceful Uses of Outer Space to review the scope of international cooperation in peaceful uses of outer space and to study legal problems arising from the exploration of outer space. In the mid-60’s, a number of questions concerning the peaceful uses of outer space were discussed in various United Nations bodies. On 19 December 1966, the General Assembly in resolution 2222(XXI) adopted the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, or "Outer Space Treaty."
The Committee then began drafting a “Rescue Agreement.” The Agreement, elaborating on elements of articles 5 and 8 of the Outer Space Treaty, provides that all States shall take all possible steps to rescue and assist astronauts in distress and promptly return them to the launching State, and that States shall, upon request, provide assistance to launching States in recovering space objects that return to Earth outside the territory of the launching State. The Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space was thus adopted in the General Assembly resolution 2345(XXII) of 19 December 1967.
Since its inception, one of the goals of the UN has been to avert nuclear war. In January 1968, a group of States under the auspices of the Conference of the Eighteen-Nation Committee on Disarmament, met in Geneva to negotiate a treaty on the non-proliferation of nuclear weapons. The draft treaty, called the Treaty of the Non-Proliferation of Nuclear Weapons, was then considered by the General Assembly, which adopted the text in resolution 2373. By this treaty, the non-nuclear-weapon states agree never to acquire nuclear weapons and, in exchange, are promised access to assistance in the peaceful uses of nuclear energy, while nuclear-weapon states pledge to carry out negotiations relating to cessation of the nuclear arms race and to nuclear disarmament. A total of 190 parties have joined the landmark international agreement, including the five nuclear-weapon States. More countries have ratified the Treaty of the Non-Proliferation of Nuclear Weapons than any other disarmament agreement.
In 1969 deliberations on acquiring a harmonious balance on all elements of social and economic development, particularly in developing countries were held in the Economic and Social Council and in the General Assembly. Subsequently, the Commission for Social Development submitted a draft Declaration on Social Progress and Development, which was adopted by the General Assembly in resolution 2543(XXIV) of 11 December 1969. This was the first time an international instrument provided clear guidelines, not only for social policies but also for the integration of economic and social action for the improvement of the social environment and the well-being of the individual.
In July 1970, young people from all over the world gathered at UN Headquarters in New York for the World Youth Assembly, the first international youth convocation organized by the United Nations. The Assembly was organized by the General Assembly as part of celebrations for the twenty-fifth anniversary of the UN. Over eleven days, 646 participants – nominated by their countries or selected by student and youth organizations – used the UN platform to discuss global issues important to them, such as education, peace, development and the environment. The success of the World Youth Assembly was noted by the General Assembly in resolution 2633(XXV). Today, as the United Nations reaches its seventy-fifth anniversary, it remains a priority for the Organization to engage young people and encourage efforts to involve them in the decisions that will shape their future.
With Secretary-General U Thant completing his second term in late 1971, the search began for a suitable successor. On 21 December, the UN Security Council recommends the appointment of Mr. Kurt Waldheim, a long-serving diplomat from Austria and that country’s former Permanent Representative to the UN. The following day, the General Assembly responds by adopting resolution 2903(XXVI); thus ushering in Mr. Waldheim as the Organization’s fourth Secretary-General. He served two five-year terms beginning on 1 January 1972 and ending in 1981, after which he went on to become the ninth President of Austria.
By the 1970’s, Governments and their citizens - concerned with environmental issues such as species loss, acid rain, and pollution – agreed that a UN body should be created to coordinate the global response to environmental challenges. In 1972, the United Nations held its first major conference on international environmental issues. The United Nations Conference on the Human Environment, also known as the Stockholm Conference, was held from 5 to 16 June. The Conference's final report contained the recommendations for what would become the United Nations Environment Programme (UNEP). On 15 December 1972, the General Assembly adopts resolution 2997(XXVII) and the new United Nations environment unit is officially created. It is also agreed in resolution 3004(XXVII) that the headquarters of the programme will be located in Nairobi, Kenya. UNEP’s mission is "to provide leadership and encourage partnership in caring for the environment by inspiring, informing, and enabling nations and peoples to improve their quality of life without compromising that of future generations."
In 1946, the General Assembly adopted resolution 2(1) which addressed the rules of procedure concerning languages. It was resolved that five of them; Chinese, French, English, Russian and Spanish would be the official languages. Of these, only two; English and French would be both official and working languages. Discussions about the inclusion of other languages were held in the following years. On 18 December 1973, the Assembly, in resolution 3189(XXVIII), decides to include Chinese among the working languages of the General Assembly and the Security Council. The same day, the Assembly, in resolution 3190(XXVII), acknowledged the importance of the Arabic language among Member States by making it an official and working language of the General Assembly and its main committees. For the first time, official UN documents would be published in Arabic and the UN would offer Arabic speakers simultaneous interpretation of statements made at meetings. Today all six languages are both official and working languages of the Security Council and General Assembly and are widely used throughout the United Nations.
The sixth special session of the General Assembly was held from 9 April to 2 May 1974. In his address, the Secretary-General Kurt Waldheim said that the aim of the special session was “to secure optimum use of the world's natural resources for better conditions of social justice throughout the world.” The general debate - in which 107 Member States presented their views - focused on the question of raw materials and development. At the close of the session on 1 May 1974, the Assembly adopted a Declaration and a Programme of Action on the Establishment of a New International Economic Order in resolutions 3201(S-VI) and 3202(S-VI) respectively. In this Declaration, the General Assembly proclaimed its “determination to work urgently for the establishment of a new international economic order, based on equity, sovereign equality, interdependence, common interest and co-operation among all States, which was to correct inequalities and redress existing injustices, eliminate the gap between developed and developing countries and ensure economic and social development, peace and justice for present and future generations.”
1975 was proclaimed to be International Women's Year by the General Assembly in resolution 3010(XXVII) of 18 December 1972. The objectives of the year were “to promote equality between men and women, to ensure the full integration of women in the total development effort, and to recognize the importance of the increasing contribution of women to the development of friendly relations among States and the strengthening of international peace.” The year culminated in the World Conference of the International Women's Year held in Mexico City from 19 June to 2 July 1975. One hundred and thirty-three governments participated, while 6,000 NGO representatives attended a parallel forum, the International Women’s Year Tribute. The conference's outcome document, The Report of the World Conference of the International Women's Year, contains the Declaration on the Equality of Women and their Contribution to Development and Peace and a defined World Plan of Action for the Implementation of the Objectives of the International Women’s Year. Later in the year, the General Assembly in resolution 3520(XXX) would reaffirm the results of the conference. Since this inaugural conference in Mexico City, the United Nations has organized three world conferences on women: Copenhagen (1980), Nairobi (1985), and Beijing (1995).