One of China’s highest-ranking military officials is under investigation for “serious discipline violations,” Beijing announced Thursday, using a common euphemism for corruption.

The announcement marks a notable escalation in Chinese leader Xi Jinping’s campaign to tackle the long-standing graft that has reached the top rungs of the Chinese army.

The Chinese Communist Party decided to suspend Admiral Miao Hua - who has headed the powerful political work department of its Central Military Commission since 2017 - pending an investigation, Wu Qian, a Defense Ministry spokesman, said at a news briefing Thursday.

Xi has promised to stamp out bribery and disloyalty among the military’s top brass, warning of a “seriously polluted political environment” that has damaged its image.

A clear-out has been going on for more than a year and has netted dozens of generals and other high-ranking officials, including the last two defense ministers - Li Shangfu and Wei Fenghe - who were expelled from the Communist Party in June.

Many of those who have disappeared or been dismissed were connected to procurement of weapons or to the Rocket Force, which oversees China’s expanding arsenal of nuclear weapons and ballistic missiles.

Miao’s downfall indicates that Xi is far from finished with his efforts to bring the People’s Liberation Army in line.

Daniel Mattingly, associate professor of political science at Yale University, described the move as “remarkable.”

“Xi Jinping is clearly laser-focused on making the PLA less corrupt and more capable and professional, and he has the institutional power and personal prestige to keep sacking these top generals without meeting real blowback,” Mattingly said.

Thursday’s announcement follows a report in the Financial Times this week that Defense Minister Dong Jun, who has been in the role for less than a year, was also under investigation.

On Thursday, China’s Defense Ministry dismissed the Financial Times article, which cited anonymous U.S. officials, as “pure fabrication.”

Asked who was currently defense minister, spokesman Wu called the question “nonsensical” and added, “I just said ‘Minister Dong Jun’ many times.”

Dong was at a regional defense meeting in Laos last week, where he declined to meet with U.S. Defense Secretary Lloyd J. Austin.

The Pentagon called the snub “unfortunate” at a time when military tensions remain high in the South China Sea and around Taiwan, the island democracy Beijing claims as its own.

The pair first met in May, which was also the first top-level meeting of American and Chinese military officials in the past two years. Before their most recent promotions, Miao and Dong held senior positions in the navy, a branch of the military that had been mostly spared in the crackdown until now.

Miao was widely seen by experts on Chinese politics as having backed Dong’s ascension.

Drew Thompson, an expert on the Chinese military at the S. Rajaratnam School of International Studies in Singapore, said Miao’s position as head of political work on the Central Military Commission made him more powerful than Dong or his two predecessors.

Under the Chinese system, defense ministers act primarily as a point of contact with other countries’ militaries and do not control budgets or command forces.

Because the Chinese military is the armed wing of the Communist Party, the removal of its most senior political officer is very serious, Thompson said.