The top U.S. military commander in the Pacific recently warned lawmakers that China's expanding air force is rapidly narrowing America's long-standing aerial advantage in the region and could soon prevent the United States from achieving air superiority across the first island chain -- the crucial expanse of Western Pacific territory that includes Taiwan and parts of Japan and the Philippines. Adm. Sam Paparo, commander of U.S. Indo-Pacific Command, detailed the scale of China’s growing airpower and the operational risk it...