琉球原非美國在東亞最為重視的地區，但隨二戰之進行而重要性大幅上升，也讓美國在認識有限的情況下，開啟其管控琉球的時代。然因此時美國的東亞決策機制具有「奥林帕斯難題」的內涵，常在內部協調尚不充分便已然行之於世的基礎上逐步調整，難以面面俱到，也令琉球必須在美國的冷戰需求，及日本的戰後期待之間游移，衍生未來問題。另也因為此時美國雖對琉球的細節不夠理解，卻因戰略需求而已有確保戰後能在東亞保持優勢的基本目標。於是其常宣稱的「門戶開放」精神再不復見，而係基於冷戰的可能到來轉向封閉。故雖美國常將「開放」用以對外宣傳，但在二戰行將結束之際，對於過去曾因其門戶開放政策受惠的東亞地區，卻反其道而行，琉球即是其中一例。本文擬就美國自二戰後期以來對此地區的名稱界定及範圍劃定歷程，及其運作過程中遇到的狀況，探討該過程的實施原因與影響。期能對此延伸至今日、時而發生海上衝突甚至外交糾紛的國際問題，獲致相對接近事實的歷史認識，藉以理解美國戰後規劃及東亞冷戰發展歷程之間的關聯情形。

As the Second World War came to the end, the United States gradually attached more importance to the East Asian region and eventaully enforced its administration in Ryukyu since 1945. However, the US neither got enough information about Ryukyu nor the internal consensus before its control in the islands, which revealed the “Olympians Dilemma” in the US Decision-making. The “Olympians’ Dilemma” not only caused problems in the relationship among the US, Japan and Ryukyu, but also harmed the essence of “Open Door Policy” in the US diplomacy. The US tried to establish Ryukyu as a good strategic beachhead in East Asia after the War; nevertheless, it did not have time to make a flawless plan before the coming of the Cold War. Therefore, it faced the outcome of the dilemma and an unopened US-contained Ryukyu. It led an example for the idealized harmonious East Asia as an unfulfilled ambition of the US and certain international conflicts in the area today, even though the slogan was still used to be a government's propaganda of the US. The paper focuses on the approach of Diplomatic History for reading the official archives of the Foreign Relations of the United States (FRUS) and of the Ministry of Foreign Affairs of Republic of China to investigate the progress and influence of the definition of the name and range of Ryukyu since the later period of WWII, and further discusses the relations to the current maritime and diplomatic conflicts in East Asia.