Because of anti-communist sentiment at the start of the Cold War, the Republic of China was initially recognized as the sole legitimate government of China by the United Nations and most Western nations. On 9 January 1950, the Israeli government extended recognition to the People's Republic of China. United Nations General Assembly Resolution 505, passed on 1 February 1952 considered the Chinese communists to be rebels against the Republic of China. However, the 1970s saw a switch in diplomatic recognitions from the ROC to the PRC. On 25 October 1971, Resolution 2758 was passed by the UN General Assembly, which "decides to restore all its rights to the People's Republic of China and to recognize the representatives of its Government as the only legitimate representatives of China to the United Nations, and to expel forthwith the representatives of Chiang Kai-shek from the place which they unlawfully occupy at the United Nations and in all the organizations related to it."  Multiple attempts by the Republic of China to rejoin the UN, no longer to represent all of China but just the people of the territories it governs, have not made it past committee, largely due to diplomatic maneuvering by the PRC, which claims Resolution 2758 has settled the matter. The PRC refuses to maintain diplomatic relations with any nation that recognizes the ROC, but does not object to nations conducting economic, cultural, and other such exchanges with Taiwan that do not imply diplomatic relation. Therefore, many nations that have diplomatic relations with Beijing maintain quasi-diplomatic offices in Taipei. Similarly, the government in Taiwan maintains quasi-diplomatic offices in most nations under various names, most commonly as the Taipei Economic and Cultural Office.
Question: What has kept the Republic of China from rejoining the UN?
Answer: diplomatic maneuvering by the PRC