Recently, four Chinese students who travelled to the United States to study and participate in academic conferences suffered from the US side's unwarranted harassment, interrogation and repatriation, sources said.

All of them have scientific and technical backgrounds, and "two of them have research interests in artificial intelligence", the sources familiar with the matter told China Daily with the condition of anonymity.

The officers with US Customs and Border Protection took the four Chinese individuals to a dark room for more than 10 hours of continuous interrogation and repeatedly questioned them in a baiting, coercive approach, the sources unveiled.

The officers repeatedly questioned them about their personal and family information, their studies and internships in the US, whether they were members of the Communist Party of China, and whether they had cooperated with the Chinese government.

Such officers "paid particular attention to political backgrounds such as CPC membership, and to scientific research backgrounds related to computers", the sources said.

In addition, in the absence of fact-based evidence and valid warrants, the US side arbitrarily seized the electronic products of one of the Chinese individuals and repatriated the other three.

The US side also refused to allow two of the individuals to contact their families and friends, causing one of them to be out of contact with the outside world for more than 30 hours, the sources said.

According to incomplete statistics, the US side in recent years has conducted unwarranted harassment, interrogation and repatriation upon more than 30 Chinese students majoring in computer-related fields.

The vast majority of them are master's or doctoral degree candidates, more than half of them are PhD candidates, and most of them are with well-known universities in the US.

Their research interests cover fields such as artificial intelligence, information science, network security, electronics, software engineering and electronic information engineering.

"Mostly, these students were harassed and interrogated by the US side for more than 10 hours upon entering the country, and the longest time of being held was even up to 5 days, and ultimately, without exception, their visas were cancelled and they were repatriated," the sources said.

The US practices are "far beyond the realm of normal law enforcement, is strongly ideologically biased and is not aimed at maintaining the so-called ‘national border security'," they added.

The purpose of such an approach is to hold back China's scientific and technological development and maintain US scientific and technological hegemony, which "fully reflects the hegemonic, bullying nature of the US side, as well as its anxiety and lack of self-confidence in the realm of science and technology", the sources said.

The US practices will only give rise to a serious "chilling effect" inside and outside the US, poison the public opinion environment for China-US relations, and impede the mutual visits and exchange of talents between the two countries, they added.

In doing so, the US will eventually damage its own international image and innovation vitality, and lead to a serious backfire, they said.

"Chinese students should assess the risk with great caution and think twice before going to the US to study," the sources said.