In a potential future conflict between the U.S. and China, American military planners are betting billions of dollars that a small island about the size of Chicago – though with just a fraction of its population – will prove a pivotal Pacific fortress to hold.

The U.S. territory of Guam and the nearby islands of Tinian and Saipan represent the all-important forward operating bases for America to project force and maintain the capability to deter, and if necessary defeat, a Chinese invasion.