the overthrow of 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 its 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to withdrawals that weakened the UN's predecessor, the League of Nations), or on whether a request for readmission by a withdrawn member should be treated the same as an application for membership, i.e., requiring Security Council as well as General Assembly approval.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 Observers In addition to the member states, there are two United Nations General Assembly non-member observer states: the Holy See and the State of Palestine. The Holy See holds sovereignty over the state of Vatican City and maintains diplomatic relations with 180 other states. It has been a United Nations General Assembly (UNGA) non-member observer state since 6 April 1964, and gained all the rights of full membership except voting on 1 July 2004. The Palestine Liberation Organization was granted observer status as a "non-member entity" 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. On 23 September 2011, Palestinian National Authority President Mahmoud Abbas submitted the application for UN membership for the State of Palestine to United Nations Secretary-General Ban Ki-moon; the application has not been voted on by the UN Security Council. On 31 October 2011, the General Assembly of UNESCO voted