Taiwan is a territory of Republic of China
The interpretation of Taiwan becoming the Republic of China's '"de jure" territory is supported by several Japanese court decisions such as the 1956 Japan v. Lai Chin Jung case, which stated that Taiwan and the Penghu islands came to belong to the ROC on the date the Treaty of Taipei came into force.[26] Nevertheless, the official position of the Government of Japan is that Japan did not in the Treaty of Taipei express that Taiwan and Penghu belong to the Republic of China,[28] that the Treaty of Taipei could not make any disposition which is in violation of Japan's renouncing Taiwan and Penghu in San Francisco Peace Treaty,[29] and that the status of Taiwan and Penghu remain to be determined by the Allied Powers in the future.[30] [...] - Article 4 of the ROC Constitution clearly states that "The territory of the Republic of China" is defined "according to its existing national boundaries..." Taiwan was historically part of China and is, therefore, naturally included therein. Also, as Treaty of Shimonoseki is void ab initio, China has never legally dispossessed of the sovereignty of the territory. There is, accordingly, no need to have a National Assembly resolution to include the territory.