This book reveals the nature of Sino-US strategic competition by examining the influence exerted by major secondary stakeholders, e.g. Japan, Russia, India, the Koreas, and ASEAN, on the two powers, USA and its rival China, who consider each other as a source of greatest challenges to their respective interests. By adopting strategic triangles as the analytical framework and assessing triangular relational dynamics, such as US-China-Japan or US-China-Russia, the author illustrates how secondary stakeholders advance their own interests by exploiting their respective linkages to the two rivals, thereby, shaping Sino-US completive dynamics. This work adds a regional and multivariable perspective to the understanding of the Indo-Pacific's insecurity challenges.