Why is it so difficult for a great power or a hegemon to retrench its overseas military power? Specifically, why are U.S. military bases and troops still largely where they were five years ago, twenty years ago, or even seventy years ago? Through developing a theory of great-power persistence, this book offers an explanation. Closely aligned with neoclassical realism, the theory argues that the murkiness of the anarchic international system combines with specific psychological inclinations of individuals to produce “better-safe-than-sorry” policies. In the United States, decisions on troop deployments are powerfully influenced by the broader foreign-policy community. Its members tend to be risk-averse and highly sensitive to the possibility that even minor troop withdrawals might set off harmful geopolitical chain reactions. Preferring the status quo over any uncertain alternative, they want their country to continue to maximize its influence and project its military power abroad in order to steady wobbling geopolitical “dominoes.” The theory is put to the empirical test through a systematic analysis of U.S. overseas troop deployments, withdrawal attempts, and retrenchment resistance during the presidency of Donald Trump, which represents an ideal test case for these mechanisms. Even if U.S. voters elected a retrenchment advocate as president, and despite that the United States is a gradually declining power, the period saw very little change in U.S. overseas troop deployments. The book concludes that, barring any dramatic, unforeseeable international event, the vast network of overseas U.S. military bases and troops is likely to persist for a long time to come.

为什么一个大国或霸主如此难以缩减其海外军事力量？具体来说，为什么美国的军事基地和军队在很大程度上仍然在五年前、二十年前、甚至七十年前的位置？通过发展大国持久性理论，本书提供了一个解释。该理论与新古典现实主义密切相关，认为无政府的国际体系的模糊性与个人的特定心理倾向相结合，产生了 "安全比遗憾好 "的政策。在美国，关于部队部署的决定受到了更广泛的外交政策界的强烈影响。其成员倾向于规避风险，对即使是轻微的撤军也可能引发有害的地缘政治连锁反应的可能性高度敏感。比起任何不确定的替代方案，他们更倾向于维持现状，希望自己的国家继续最大限度地发挥其影响力，并将其军事力量投射到国外，以稳定摇摆不定的地缘政治 "多米诺骨牌"。该理论通过对唐纳德-特朗普担任总统期间的美国海外军队部署、撤军企图和缩减阻力的系统分析进行了实证检验，这代表了这些机制的理想测试案例。即使美国选民选出了一个主张缩减的人作为总统，尽管美国是一个逐渐衰落的大国，但这一时期美国的海外部队部署几乎没有变化。本书的结论是，除非发生任何戏剧性的、不可预见的国际事件，否则庞大的美国海外军事基地和部队网络可能会在未来很长一段时间内持续存在。