Abstract: In light of the first Japan-India-Australia Trilateral Dialogue that took place in June 2015, this paper analyzes 1) why these countries opted not to include the US in the dialogue; and 2) how such trilateral cooperation could help maintain security in the Indo-Pacific. In answer to the first question, the author suggests that a key reason might be that the Trilateral Dialogue is part of an attempt to create a much-needed security framework within the region in light of the shift in the balance of power between the US and China in the Indo-Pacific. In answer to the second, he suggests that Japan-India-Australia trilateral cooperation – through helping maintain the balance of power in the region by increasing information sharing, capacity building and the ability of the three states to enhance their regional presence – could improve the prospects for regional security.