This chapter examines episodes of water contamination and U.S. military operations across the Pacific, including Okinawa, Hawaiʻi, and the Philippines. Through the water contamination case, this study sheds light on militarized territoriality as a phenomenon in which maintaining smooth military operations as a strategic imperative influences determination and management of uncertainties (i.e., what is considered worth securing) across territories in the Pacific while obscuring accountability of managing them. This study shows that the phenomenon is prevalent in (post)colonial islands of the Pacific whose lands are occupied or used for military purposes. In doing so, the water contamination case and the concept of militarized territoriality offer critical insights into how the U.S. geopolitical maneuvering is contingent on the ways in which its strategic imperative can be achieved while prone to interfere with island life including how the environment and health of island residents can be secured and realized. Therefore, this study suggests that centering on islands and islanders is a critical approach for studies of geopolitics to further examine manifestations of the strategic imperative and enrich the island scholarship to deepen the understanding of workings and implications of geopolitical maneuvering.