a. On 22 September 1992, United Nations General Assembly Resolution A/RES/47/1 was adopted, by which it considered that "the Federal Republic of Yugoslavia (Serbia and Montenegro) cannot continue automatically the membership of the former Socialist Federal Republic of Yugoslavia in the United Nations," and therefore decided that "the Federal Republic of Yugoslavia (Serbia and Montenegro) should apply for membership in the United Nations and that it shall not participate in the work of the General Assembly". It did not apply for membership until Slobodan Milošević was ousted from the presidency and was admitted on 1 November 2000 (see the section Former members: Serbia and Montenegro).
Withdrawal of Indonesia (1965–1966)
Since its inception, only one member state (excluding those that dissolved or merged with other member states) has unilaterally withdrawn from the UN. During the Indonesia-Malaysia confrontation, and in response to the election of Malaysia as a non-permanent member of the United Nations Security Council, in a letter dated 20 January 1965, Indonesia informed the United Nations Secretary-General that it had decided "at this stage and under the present circumstances" to withdraw from the UN. However, following the overthrow of the Indonesian regime led by President Sukarno, in a telegram dated 19 September 1966, Indonesia notified the Secretary-General of its decision "to resume full cooperation with the United Nations and to resume participation in its activities starting with the twenty-first session of the General Assembly". On 28 September 1966, the United Nations General Assembly took note of the decision of the Government of Indonesia and the President invited the representatives of that country to take their seats in the Assembly.
Unlike suspension and expulsion, no express provision is made in the United Nations Charter of whether or how a member can legally withdraw from the UN (largely to prevent the threat of withdrawal from being used as a form of political blackmail, or to evade obligations under the Charter, similar to withdrawals that weakened the UN's predecessor, the League of Nations), or on whether a request for readmission by a withdrawn member should be treated the same as an application for membership, i.e., requiring Security Council as well as General Assembly approval. Indonesia's return to the UN would suggest that this is not required; however, scholars have argued that the course of action taken by the General Assembly was not in accordance with the Charter from a legal point of view.
Observers and non-members
In addition to the member states, there is one non-member permanent observer state: the Holy See (which holds sovereignty over the state of Vatican City and maintains diplomatic relations with other states). It has been an observer state since 6 April 1964, and gained all the rights of full membership except voting on 1 July 2004. A number of states were also granted observer status before being admitted to the UN as full members, such as:
- Switzerland: 1948–2002
- Republic of Korea: 1953–1991
- Federal Republic of Germany: 1955–1973
- German Democratic Republic: 1972–1973
- Democratic People's Republic of Korea: 1973–1991
The Palestine Liberation Organization was granted observer status on 22 November 1974. Acknowledging the proclamation of the State of Palestine by the Palestine National Council on 15 November 1988, the United Nations General Assembly decided that, effective as of 15 December 1988, the designation "Palestine" should be used in place of the designation "Palestine Liberation Organization" in the United Nations System. The current status of Palestine in the UN is a "non-member entity". The Palestinian territories of the West Bank, including East Jerusalem, and the Gaza Strip, occupied by Israel with parts of them governed by the Palestinian National Authority, are referred to by the UN as "Occupied Palestinian Territory". On 23 September 2011, Palestinian National Authority President Mahmoud Abbas submitted the Palestinian application for UN membership to Un