Thus goes the central premise of deterrence theory, which says it is the credible threat of aggression — not the use of aggression — that will ensure states avoid war. This theory has dominated much of America’s strategic thinking over the past 50-plus years, but new technologies and new adversaries threaten to upend the status quo. For the first time, China has started to outpace the U.S. in critical weapons programs — the country developed a new type of weapon called a hypersonic glide vehicle as early as 2014, which can strike Taipei and the Taiwan Strait in about 20 minutes from the country’s strategic bases in the South China Sea.