In the context of growing US-Chinese rivalry in Asia Pacific region, Taiwan is gaining increasing strategic importance. Reunification of the Republic of China (ROC) and the People's Republic of China (PRC)-having profound potential economic and military implications, -would strengthen even more the power of a rising China. However, this scenario is not favorable to the United States and its most important ally in the Asia-Pacific region-Japan. Sino-Japan security relations are in at risk of further dysfunctionality in the years to come, and such a development will have strong reverberations in the Asia-Pacific regional security system. Thus, identifying aspects, elements and vectors that could drive the relations in a positive direction toward reconciliation is an urgent and essential work. This paper contends that the exacerbation of Beijing-Tokyo relations is primarily caused by developments such as the sensational growth of the Chinese economy and military capabilities, and the negligence or even failure of Washington to maintain a balance in its security relations with China and Japan.