The United States has projected power across the Pacific for more than a century. Yet few Americans know their country has a forward defensive perimeter in Asia, where more than sixty US bases support nearly 400,000 troops patrolling a vast oceanic frontier. Award-winning author and geopolitical strategist James Crabtree explores this vital geopolitical borderland and argues that the United States must urgently reinforce it―or lose its supremacy in the Pacific, and therefore the world.

Combining riveting storytelling with unprecedented access and cutting-edge analysis, The Perimeter explores the vital importance of the "first island chain," the fate of Taiwan, and the future of America's contest with China. Crabtree blends history, strategy, and first-person reportage to lay bare the traditional mechanisms of US power in the Pacific, and how they have struggled to adapt in the face of "carrier killer" Chinese missiles and other futuristic defense technologies. In this compelling journey along America's least famous border―from Hawaii and Guam to Japan, the Philippines, and Taiwan―he visits the Taiwanese beaches that would become landing zones in a Chinese invasion, gains access to American military bases where US Marines are retraining for radically new forms of warfare, and meets Asian leaders struggling to navigate between clashing superpowers.

A deeply engaging and provocative book about the geography of global power, The Perimeter addresses one of the biggest questions of the Trump era: How will America hold the line against China―and what happens if it can't?