On Saturday morning the world woke up to news that China's most senior military officer, who is second only to Xi Jinping, has been put under investigation over alleged "grave violations of discipline and the law."  The detained Gen. Zhang Youxia is a vice chairman of the Central Military Commission, the Communist Party body that controls China's armed forces, and this was a major shock given he is widely regarded as President Xi's closest ally within the military, until now.

Another shock is just what he is being investigated for. While all the initial speculation focused on corruption, The Wall Street Journal on Sunday reveals the top general is accused of leaking information about the country’s nuclear-weapons program the United States. However, this has not yet been confirmed through official Chinese statements or sources.

He is also accused of taking bribes in exchange for official actions, including elevating an officer to the post of defense minister, according to individuals familiar with a senior-level briefing on the allegations cited in this latest Wall Street Journal report.

The accusation of passing Chinese nuclear secrets to the United States is alone quite the bombshell, obviously rising to the level of treason, which could elicit the death penalty - as this represents the most severe crime against national security.

Below are some key lines from the WSJ report, which cites its unnamed exclusive sources:

But the people familiar with the briefing—which hasn’t been reported until now—said Zhang is under investigation for allegedly forming political cliques, a phrase describing efforts to build networks of influence that undermine party unity, and abusing his authority within the Communist Party’s top military decision-making body, known as the Central Military Commission.

Authorities are also scrutinizing his oversight of a powerful agency responsible for the research, development and procurement of military hardware. Those familiar with the briefing said Zhang was alleged to have accepted huge sums of money in exchange for official promotions in this big-budget procurement system. 

The most shocking allegation disclosed during the closed-door briefing, the people said, was that Zhang had leaked core technical data on China’s nuclear weapons to the U.S.

The reference to "undermining party unity" has by now become familiar in President Xi's ongoing purge of CCP sectors seen as potentially disloyal, or networks of power which present a challenge. In October this was largely the basis for the expulsion of nine senior generals, which marked one of the largest such crackdowns of top military officials in decades. 

Currently there are reports that mobile devices have been confiscated within military ranks and among officials seen as close or under the influence of Gen. Zhang.

The WSJ report is receiving significant pushback from Chinese pundits and sources:

WSJ's chief China's correspondent Lingling Wei describes, "And this is far from the end. With thousands of officers having risen through the ranks under Zhang Youxia and Liu Zhenli, these individuals now recognize they are primary targets for a systemic purge." She reports that "Mobile devices have been seized across ranks and all units are now on high alert."

Analyst Christopher Johnson, head of China Strategies Group, has meanwhile told WSJ of Zhang's rapid fall, "This move is unprecedented in the history of the Chinese military and represents the total annihilation of the high command."