Many analysts worry that improvements in Chinese missile, sensor, guidance, and other technologies will enable China to deny the U.S. military access to parts of the Western Pacific that the United States has long controlled. Although these “antiaccess, area denial” (A2/AD) capabilities are real, they are a geographically limited long-term threat. As both the United States and China deploy A2/AD capabilities, a new era will emerge in which the U.S. military no longer enjoys today's command of the global commons, but is still able to deny China military hegemony in the Western Pacific. In this new era, the United States will possess a sphere of influence around allied landmasses; China will maintain a sphere of influence over its own mainland; and a contested battlespace will cover much of the South and East China Seas wherein neither power enjoys wartime freedom of surface or air movement. This in turn suggests that the Chinese A2/AD threat to U.S. allies is real but more limited than often supposed. With astute U.S. choices, most U.S. allies in this new system will be imperfectly, but substantially, secure.