Outwardly, China’s military has never been stronger. Its naval ships venture farther across the oceans. Its nuclear force grows by about 100 warheads every year. Its military flights around Taiwan are increasingly frequent and intimidating. Every few months, China unveils new weapons, like a prototype stealth fighter or newfangled landing barges.

Internally, though, China’s military is experiencing its most serious leadership disarray in years. Three of the seven seats on the Central Military Commission — the Communist Party council that controls the armed forces — appear to be vacant after members were arrested or simply disappeared.

That internal turbulence is testing President Xi Jinping’s effort, going back more than a decade, to build a military that is loyal, modern, combat-ready and fully under his control. Xi has set a 2027 target for modernizing the People’s Liberation Army, or PLA, and also — according to some U.S. officials — for gaining the ability to invade Taiwan, which Beijing claims as its territory.