South Korea–Taiwan relations
Republic of China
The Republic of China government recognized the formation of the Provisional Government of the Republic of Korea on April 13, 1919, as one of the participants of the Cairo Conference, which resulted in the Cairo Declaration. One of the main purposes of the Cairo Declaration was to create an independent Korea, free from Japanese colonial rule. Bilateral diplomatic relations between the Government of South Korea and the Republic of China began in 1948, just after the foundation of the First Republic of South Korea.
Diplomatic relation between South Korea and Taiwan was terminated in 1992, followed by South Korean recognition of the People's Republic of China (PRC) and formation of bilateral recognition between them. Meanwhile, both countries still maintains non-diplomatic relation.
Independence of South Korea and the Korean War
The division of Korea was followed by a period of trusteeship by American occupation in the south. The first General Election of South Korean Constitutional Assembly election, 1948 founded the First Republic of South Korea under the supervision of United Nations. China recognized the Constitutional Korean government in the southern portion of the Korean Peninsula and opened an Embassy in Myeongdong, Seoul, on 4 January 1949, four months after the establishment of the Republic of Korea.
The People's Republic of China (PRC) was founded in 1949 following the Chinese Civil War and South Korea maintained relations with the Republic of China (ROC), which relocated to Taiwan. The United Nations condemned North Korea's military aggression against South Korea in United Nations Security Council Resolution 82 and United Nations Security Council Resolution 84. The ROC voted in favor of both United Nations resolution. During the Korean War, the ROC supplied material aid to South Korea, while the People's Republic of China gave North Korea combatants to support the People's Volunteer Army.
Cold War diplomacy
Both South Korea and Taiwan were countries against communism, and in opposition to the People's Republic of China (PRC). Neither South Korea nor Taiwan recognized or formed the diplomatic relationship with the PRC government. South Koreans had referred the PRC as 'Communist China'(중공, 中共), and the ROC as 'Nationalist China'(국부중국, 國府中國; before 1960s) or 'Free China'(자유중국, 自由中國; after 1970s). Taiwanese had also considered the Republic of Korea government as the sole legitimate state in Korean peninsula.
Termination of diplomatic relations
The Sixth Republic of South Korea furthered the Miracle on the Han River to the Economy of South Korea and opened diplomacy to Communist Nations (including building the foundation of Inter-Korean relations  and accepting co-existence with North Korea by entering the United Nations ). Seoul also hosted the 1988 Summer Olympics. President Roh Tae-woo's next political ambition was to begin implementing Realpolitik with the neighboring countries in Northeast Asia.
On 23 August 1992, South Korea opened diplomatic relations with the People's Republic of China. South Korea's movement away from anti-communist foreign policy to improve relations with nearby communist countries resulted in a deterioration of relations with Taiwan. This change was introduced to appease North Korea and ease the political anxiety and softens military tension in the Korean Peninsula; South Korea hoped to enable the possibility of a peaceful reunification in the Korean peninsula. As normalization begun, ROK transferred diplomatic recognition from Taiwan to the PRC, and confiscated the property of the Taiwanese embassy, transferring it to the PRC. On 17 September 1991, the PRC withdrew their objection against South Korean membership in the United Nations. South Korea was the last Asian country with formal diplomatic relations with Taiwan.
Flights between South Korea and Taiwan
After Seoul's recognition of the PRC government in Beijing, direct commercial flights between Seoul and Taipei operated by Korean and Taiwanese airlines were terminated. Cathay Pacific and Thai Airways International however, operated the route as a Fifth Freedom sector. The reduction of scheduled flights caused tourist numbers from Taiwan to drop from 420,000 in 1992 to 200,000 in 1993, recovering only partially to 360,000 by 2003.
On September 1, 2004, representatives of South Korea's unofficial mission in Taipei and Taiwan's unofficial mission in Seoul signed an aviation agreement allowing aircraft of each side to enter the airspace of the other. This permitted the resumption of direct scheduled flights by Korean and Taiwanese airlines and also allowed flights from South Korea to Southeast Asia to fly over the island of Taiwan instead of detouring over mainland China or the Philippines. Analysts estimated this would save South Korean airline companies ₩33 billion (US$29 million at 2004 exchange rates) in fuel costs and other fees.
Kim Young-sam's visits to Taiwan
Former South Korean president Kim Young-sam visited Taipei for five days in July 2001. During this visit, he met President of the Republic of China Chen Shui-Bian at a lunch banquet, but the two were unable to come to an agreement over the wording of a joint written statement urging the resumption of direct air travel. Kim informed the embassy of the People's Republic of China in advance of his visit.
In October 2004, following the aviation agreement, Kim came to Taiwan once more at Chen's invitation. He delivered a speech at National Chengchi University and toured port facilities in Kaohsiung, the sister city of South Korea's Busan.
Taiwanese admission into APEC
The South Korean government acted as the interlocutor  and supported Taipei's admission into Asia-Pacific Economic Cooperation (APEC) in 1991 as a Chinese economy. South Korea altered the nature of political acronym of Member States to Member Economies in APEC to make APEC formally a Trans-Pacific Economic Forum. Personnel of Taipei's Ministry of Foreign Affairs are forbidden to participate in the APEC, but the Minister of Economic Affairs of Republic of China, a special envoy appointed by the President of Republic of China and business representatives from Republic of China that publicly, can attend annual APEC Meetings under the name of Chinese Taipei. Taipei can also host non-ministerial APEC consortiums and workshops concerning topics in which Chinese Taipei has specific strengths, such as technology and small and medium enterprise. These consortia and workshops are intended to address only success on economics and business-related issues with other APEC Member Economies. Chinese Taipei's participation in APEC is supported by the United States and accepted by People's Republic of China. The APEC Business Travel Card (ATBC) scheme applies to business travelers to and from Chinese Taipei.
Re-establishing non-official relations
Republic of Korea re-established non-official relations with Republic of China in 1993, interchangeably and reciprocally as Korean Mission in Taipei and Taipei Mission in Korea. Taipei Mission in Korea, Busan Office is located in the southern region of ROK. Since 1993, there is significant trade volume between the two nations. Two countries have mutually extended to 90 days of stay with the exemption of visa for visitors from July 1, 2012. The 19th Seoul-Taipei forum was held on October 13th 2010. 
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