China’s highest-ranking general, second only to President Xi Jinping himself in the military command, has been placed under investigation and accused of “grave violations of discipline and the law,” the country’s defence ministry announced on Saturday, the most stunning escalation so far in Xi’s years-long purge of the People’s Liberation Army.

The ministry announcement of the investigation gave no details about the alleged misconduct of the general, Zhang Youxia, the vice-chairman of the Central Military Commission, the Communist Party body that controls the armed forces. It also said General Liu Zhenli, another member of the commission and the chief of the military’s joint staff department, was under investigation.

General Zhang’s downfall is the most drastic step so far in Xi’s campaign to root out what he has described as corruption and disloyalty within the senior ranks of the military. It is all the more astonishing because General Zhang had appeared to be a confidante of Xi.

With the investigations of Generals Zhang and Liu, the Central Military Commission is now left with only two members: Xi, who chairs the body, and General Zhang Shengmin, who has overseen Xi’s military purges. Five of the six uniformed commanders whom Xi appointed to the commission in 2022 have now been removed.

General Zhang, 75, had appeared to be close to Xi. Their fathers were both veterans of Mao Zedong’s revolutionary wars and were personally acquainted, and Xi kept General Zhang in office beyond the customary retirement age. But widening corruption investigations and other possible violations appear to have eroded Xi’s confidence in him.

“This move is unprecedented in the history of the Chinese military and represents the total annihilation of the high command,” Christopher K. Johnson, a former Central Intelligence Agency analyst who closely follows Chinese elite politics, said of the investigations. Xi appears to have decided that problems in the Chinese military run so deep that he cannot trust the current command to cure itself, said Johnson, who is also president of China Strategies Group, a consulting firm.

Xi appears to have “decided he must cut very deep generationally to find a group not tainted,” Johnson said.