When imagining how the U.S.-Chinese relationship might devolve into war, experts often cite Taiwan as the most obvious flash point. In recent years, after all, China has escalated its campaign of coercion against the island democracy, lobbing missiles over it, staging a blockade during live-fire military exercises, and threatening catastrophic punishments against third countries that expand ties with Taipei. Although the United States does not have a defense treaty with Taiwan, Beijing’s aggression against the island—paired with Chinese President Xi Jinping’s reported desire to be capable of invading by 2027—has prompted the U.S. military and policy community to accelerate steps that would strengthen cross-strait deterrence. But if conflict does break out in the Western Pacific, it is more likely to erupt southwest of Taiwan , in the South China Sea, where numerous countries jostle over competing maritime claims and divergent visions of sovereignty, regional order, and international law.…