China removed former Foreign Minister Qin Gang from the post after an investigation concluded he’d conducted an affair and fathered a child while serving as US ambassador, the Wall Street Journal reported.

Top officials were told in August that a Communist Party inquiry into Qin uncovered “lifestyle issues,” the newspaper reported Tuesday, citing people familiar with the situation that it didn’t describe. That phrase usually means sexual misbehavior of some type in the parlance of Chinese officialdom.

Two of the people said the affair led to the birth of a child in the US. The probe, with Qin’s assistance, is now focusing on whether or not the affair compromised national security. China is locked in an ideological battle with the US, its chief economic and geopolitical rival, which has seen Beijing intensify a national security drive to shield it from foreign threats.

The Foreign Ministry in Beijing didn’t immediately respond to a request for comment on Tuesday.

China stripped Qin from his ministerial post in July, just seven months after he started the job – making his tenure the shortest in that role. No explanation was given for Qin’s removal as his predecessor Wang Yi was reinstated.

The episode raised questions over President Xi Jinping’s decision-making and the stability of the government running the world’s No. 2 economy. Those concerns are being rekindled by the current unexplained absence of Defense Minister Li Shangfu, amid media reports he’s being probed for corruption.

The ruling Communist Party’s senior ranks are now being scrutinized for their dealings with foreigners, the insiders told the WSJ, adding that the top brass in China’s military were also under the spotlight.