Since the beginning of the 21st century, the People’s Liberation Army (PLA) of China has undergone a period of rapid modernization of its air, sea, land, space, and cyber forces, creating concern about the relative rate of U.S. modernization efforts. Prior research documents the seemingly slow response of the U.S. Department of Defense (DoD) to modernize its forces. China’s investments in modernization have upset the conventional military balance, undermined the U.S. ability to deter China’s aggression in the Indo-Pacific region, increased the cost and risks of war if deterrence fails, and complicated U.S. policymakers’ decision space by ensuring that any conventional war will be fought with the risk of nuclear escalation.