近年來，東北亞海域風雲迭起，中日之間屢屢發生主權爭議。從表面上看，似乎與雙方海洋主權、經濟資源等利益有關；但若追根究底，則問題出在東北亞海洋地理之衝突本質。因為日本與中國同處一域，但日本是海島國家，而中國是海陸兼具大國。雖然過去歷史裡，中國迫於北方威脅而把自己想成陸上強權﹔但是，隨著改革開放之經濟成長，在能源與海洋運輸需求日增之下，使中國不得不重新認識國家海洋利益之重要性。簡單的說，正因為中國海權崛起，顯現出東北亞海域難以容下兩個海上強權之事實；也因為中國海權崛起，直接挑戰了日本國家安全之核心利益，以及甲午戰爭以來由日本所主導的東北亞海上秩序。因此，基於上述認識，使得日本重新思考其國家安全戰略而做出再演進之策略，此不僅因東北亞地緣政治格局之轉變，也與東北亞海洋地理之衝突本質有關。

In recent years, the maritime claims between China and Japan have increasingly arisen such as the dispute about the Diaoyutai Islands (or the Senkaku Islands), the China vessel crossing the region of Ryukyu Islands, and the ADIZ (Air Defense Identification Zone). Seemingly, the conflict of the ＂National Strategy＂ on the two sides is related to the national interests deriving from the marine sovereignty, marine economy and resources. As a matter of fact, these disputes result from the intrinsic quality of the marine geography and geopolitics in Northeast Asia. Although Japan and China are situated in Northeast Asia, Japan is a country of islands and China is a country of land with a long stretch of coastline. Once China's military power is on the rise, especially in the Sea Power, it would challenge the core of national interests of Japan. Furthermore, it would change the maritime order in East Asia after the First Sino-Japan War in 1894. In other words, the international relations of different phases have an impact on the balance of power. Thus, the sea-power against land-power in traditional geopolitics will dynamically change with international events. Therefore, the above understanding, which makes Japan rethink over its national security strategy, in turn, causes not only the transformation of the geopolitics of Northeast Asia but also the conflict of the marine geography.