In the early 1970s, overseas Chinese students in the United States protested against Japan's claim to the Diaoyutai Islands. Emerging at a time when the rivalry between the Republic of China (ROC) in Taiwan and the People's Republic of China (PRC) on the mainland to represent China was at a critical juncture, the movement soon found itself caught up in the struggle between the two sides. It was out of the Protect Diaoyutai Movement that a new ideological constituent of overseas Chinese nationalism came to light, looking to the PRC as the hope for a sovereign China. It became a predominant force among overseas Chinese activists and the movement changed its direction from defending Diaoyutai to seeking Taiwan's reunification with the mainland. The paper discusses the factors that shaped and eventually radicalized the movement. It asserts that the event was a turning point in the evolution of overseas Chinese nationalism which transformed an undercurrent into a surging tide that gave rise to a new Chinese national identity among overseas Chinese in America.