Abstract: This paper will analyze why and how US-Japan-Australia security cooperation developed in the 2000s, mainly from the allied perspective (Japan and Australia). Existing literature notes that the United States aimed to form an alliance opposing China from the start of the 2000s by strengthening relationships with its allies. In contrast, Japan and Australia’s perception of China was different to that of the United States. This especially applied to Australia, geographically distant from China, which prioritized strengthening its relations with China through diplomacy and trade over direct antagonism. Regardless of this, both Japan and Australia worked to strengthen security cooperation between Japan, the United States, and Australia based on a strategy of “supplementing” the United States’ regional and global role by furthering cooperation between its allies in peacekeeping operations and non-traditional areas of security. The strengthening of security cooperation between Japan, the United States, and Australia during the 2000s developed in order to maintain and enhance the United States’ presence based on the “hub and spokes” alliance system, rather than to directly oppose China. Full text available here.