Stretching from Kyushu southwestward toward Taiwan, the Ryukyu island chain forms a natural barrier between the East China Sea and the Philippine Sea. The chain includes Okinawa — site of the largest American military concentration in the western Pacific — and continues through progressively smaller islands to the Yaeyama group, whose southernmost point lies less than 75 miles from Taiwan’s northeastern tip. This geography is not coincidental to the Taiwan question. It is central to it. Any Chinese military operation in the Taiwan Strait must account for the Ryukyu chain, and any American or Japanese response to such an operation would use the chain as its primary operating framework.