SINGAPORE - The Singaporean who spied on the United States for China has been arrested by the Internal Security Department on his return to Singapore on Wednesday (Dec 30).
Dickson Yeo Jun Wei, 39, had been sentenced to 14 months' jail in the US for spying, and he revealed to investigators there that his "previous intelligence taskings targeted other states apart from the US", said the ISD in a release on Wednesday.
The ISD will interview Yeo to establish if he had engaged in "activities prejudicial to Singapore's security".
"Singapore will not allow our nationals to be subverted or used by any foreign actors for activities prejudicial to our security and national interests," said the department.
"The Government takes a very serious view of any Singaporean who enters into a clandestine relationship with a foreign government and engages in espionage or subversive activities at the behest of the foreign power."
The ISD added that such individuals will be firmly dealt with.
It cannot provide any further information, as investigations are still being done.
The ISD also said that precautionary measures are in place to ensure there is early detection, infection control and safe distancing in the facility where Yeo is being held.
"Precautionary measures were taken during the arrest process to safeguard the health of personnel involved," said the department, adding that Yeo was still subject to the "prevailing border control requirements" when he arrived in Singapore.
The ISD added that it has informed Yeo's family members of his arrest and that the department is in contact with them, should they need any assistance.
However, as it is still investigating Yeo, he may be denied calls and visits, it said.
Yeo had pleaded guilty in July this year, to obtaining sensitive information from Americans under the direction of Chinese intelligence officials.
He had maintained that he was supportive of the Chinese "cause" even towards the end of his court hearings and he claimed that he did not "betray Singapore".
He spied on the US for four years, after being recruited by Chinese intelligence officials in 2015, when he visited Beijing for a presentation on the political situation in South-east Asia.
The then PhD student at the Lee Kuan Yew School of Public Policy was tasked by Chinese intelligence to spot and assess American citizens, including US military and government employees, who had access to valuable non-public information.
Yeo admitted that he paid American citizens to write reports that he then sent to the Chinese government without the writers' knowledge.
He set up a fake political consultancy to do so and trawled through social networking sites to find his targets.
He was caught and arrested in the US in November 2019.
After news broke of Yeo's arrest, China denied recruiting him as a spy and accused the US of having reached "a state of extreme suspicion".
Yeo's PhD candidature was terminated when the school learnt of his espionage activities.