要理解東亞地區的權力變遷，必須要先理解東亞地區內的權力結構。東亞地區內存在二個具有決定性的大國，一個是美國、一個是中國。二者的差異在於美國是全球性的主導國家，從全球的觀點看東亞的權力布局；而中國是崛起的區域強國，從本身的利益看東亞的權力問題。美、中這二個可稱之為「現狀霸權」與「崛起強國」個國家，其互動同時蘊含「合作」與「競爭」的雙重意涵，尤其是近年來在東海及南海議題處理的角力上，可看出美、中關係存在著奧妙的關係。而美國宣示重返亞洲與中國在海洋主權議題上轉趨強硬的發展，都攸關區域的安全與穩定，值得持續關注。本文藉由國際關係的「權力轉移理論」（Power Transition Theory）分析美國與中國的實力消長對於東亞安全局勢的影響，並就權力轉移理論的觀點，探討美國與中國的關係在未來的發展究竟是競爭還是合作？以及美中關係發展對東亞權力結構的影響，以作為關注當今東亞局勢發展的讀者之參考。

It is necessary to analyze the power structure in East Asia before we can understand the power transition in this area. There are two influential powers in East Asia at the presence, the United States and the People's Republic of China. As a globally dominant power, the United States views the East Asia from a perspective of global politics. China, as an emerging regional power on the other hand, tends to view the power politics in East Asia based on its own national interest. The United States which and China thus have interacted with each other both cooperatively and competitively. This complicated relationship has been fully reflected by their struggle in dealing with the territorial disputes in the East China Sea and South China Sea. Both the U.S. pivot to Asia and China's assertiveness on maritime sovereignty will have impacts on the security and stability in East Asia. This paper will analyze the change in power between the U.S. and China and its impacts on security situation in East Asia based on the Theory of Power Transition. It will also explore the future power structure due to the interaction between the two states in the region.