In October 1950, a revised draft resolution on Formosa written by the UK delegation to the United Nations clarified that despite the statements made in the Cairo Declaration (December 1, 1943), no legal change in the status of Formosa as Japanese territory had yet been effected . . . .
Telegram: United States Representative at the United Nations (Austin) to the Secretary of State (Acheson)
Date: October 11, 1950
Subject: Revised UK draft resolution on Formosa
. . . . Noting (A) That the signatories to the Cairo declaration declared it to be one of their purposes that all the territories that Japan had stolen from the Chinese, including Formosa, should be restored to the Republic of China;
(B) That no legal change in the status of Formosa as Japanese territory has yet been effected, although at the end of hostilities with Japan, China was permitted to assume the administration of the island, . . . .
[ source: United States Department of State / Foreign relations of the United States, 1950. East Asia and the Pacific, Volume VI (Document 322) ]
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[Chinese version] https://www.twdefense.info/trust3/frusch-1950an.htm