1939年日本占領南沙群島、西沙群島、東沙群島,並將南沙群島置於臺灣總督府高雄州高雄市的行政管轄之下。日本戰敗後,由中華民國軍隊接收日軍在西沙群島和南沙群島的投降。中華民國從1945年11月起即陸續完成對西沙群島和南沙群島這兩個群島的占領及行政建制,並派官治理。1951年9月8日《舊金山和約》簽署到隔年(1952年)4月28日生效,在這一段時間中華民國擁有這兩個群島的主權一直有效存在,在舊金山和議時關於中華人民共和國和越南宣稱擁有這兩個群島的提案都遭到反對或不予討論。從《舊金山和約》和《中日和約》生效日起,中華民國是第一個繼續保持占有及先占該兩個被放棄的領土。 Japan occupied the Paracel and Spratly Islands in 1939, and annexed the Spratly Islands into the administrative jurisdiction of Kaohsiung, Taiwan. After World War II, the military of the Republic of China was responsible for receiving the surrender of the Japanese army of both groups of Islands. "The San Francisco Peace Treaty of 1951" required that Japan renounce the right, title and claim to the Paracel and Spratly Islands. Based on the principles of "uti possidetis" and occupation, the Republic of China has occupied those two renounced islands/territories for long time, and hence it enjoys the sovereignty right of both two islands since the critical date.