Theory of the Undetermined Status of Taiwan (Chinese: 台灣地位未定論), also called Theory of the Undetermined Sovereignty of Taiwan (Chinese: 台灣主權未定論), is a theory about the undetermined legal status of the island of Taiwan. It is one of the theories which describe Taiwan's present status.
The theory originated from president of the United States Harry S. Truman's statement on June 27, 1950, regarding the Korean War, which had broken out two days earlier. In his statement, Truman said that it would be a direct threat to the United States' security in the western Pacific area if the communist forces occupied Taiwan, so he ordered the 7th Fleet to enter Taiwan Strait to prevent any attack on the island. Truman stated: "The determination of the future status of Formosa must await the restoration of security in the Pacific, a peace settlement with Japan, or consideration by the United Nations." Because of the statement, the Theory of the Undetermined Status of Taiwan came into existence.
Although Japan concluded the Treaty of San Francisco with the Allied Powers after World War II in 1951, in the treaty it merely "renounced" all right, title and claim to Taiwan and the Pescadores without explicitly stating the sovereignty status of the two territories. Therefore, the Theory of the Undetermined Status of Taiwan is still supported by some politicians and jurists to this day.
Supporters of the theory include but are not limited to supporters of Taiwan independence movement. They believe that Taiwan's status should be determined by Taiwanese people through self-determination.