A Chinese academic linked to Yeo Jun Wei, the Singaporean consultant who pleaded guilty to spying for Beijing, said he was happy that his former student was apprehended by US authorities.

Huang Jing confirmed to Bloomberg Television that he served as a PhD adviser a few years ago to the man, also known as Dickson Yeo, when both were at National University of Singapore’s Lee Kuan Yew School of Public Policy.

Yeo admitted on Friday that he provided information to Chinese intelligence and knowingly recruited others in the US to do the same, according to a US Department of Justice statement.

“I was really surprised, but I’m glad that he was caught,” said Huang, who’s now a distinguished professor and dean at Beijing Language and Culture University’s Institute of National and Regional Studies.

“He impressed me as someone who is shy, but also humble,” he said. “But he has this kind of hunger for being somebody. You know self-imposed importance – after that I don’t have much impression of him.”

Yeo’s case has led to renewed interest in Huang’s 2017 expulsion from Singapore, where he had been a visiting professor at the prestigious policy school.

Singapore authorities revoked Huang’s permanent residency after accusing him of using his position to covertly advance the agenda of an unnamed foreign country at Singapore’s expense – a charge Huang denies.

Huang, a US citizen, said he had a few meetings with Yeo over the course of a year at the Lee Kuan Yew school, but never saw the Singaporean student after he left to be visiting scholar in the US.

The Yeo case was one of numerous spying allegations traded by the US and China in recent days, as the Trump administration took the unprecedented step to close the Chinese embassy in Houston.

On Monday, Chinese officials took over the American consulate in Chengdu, which Beijing had ordered closed in retaliation Friday.

While each side accused the other’s diplomats of compromising their national security, the Trump administration went further, with officials telling a briefing on Friday that the FBI has about 2,000 active cases related to Chinese counter-intelligence operations in the US.

Separately, US officials said they took custody of a Chinese researcher who had taken shelter at the country’s San Francisco consulate after she was charged with trying to hide her military background.

Asked whether China commonly used students to gather information from foreign countries, Huang said that he was not familiar with such cases.

“All of this has to be done under the table,” he said. “I don’t think it’s a public campaign and so, for a scholar like me, I’m not aware of things like that.”

Huang also described Trump’s policies on China as “quite unpredictable”, but suggested that given the right conditions China might be willing to cool tensions down.

“If the US does something further to challenge China, China will retaliate and that will lead to a downward spiral,” Huang said. “But if the US – especially President Donald Trump – will not go any further, China is very happy to stop right here.”