Editor's note: A number of Chinese American scientists, researchers and engineers have been investigated by the Federal Bureau of Investigation since late 2017 on the suspicion of working for China in the United States. Mo Nong, a Beijing-based commentator, comments in a recent post on his WeChat account:

In whatever fields of science and technology these investigations were carried out, they shared one thing in common: There was no reliable evidence confirming the suspicions, which can only be called "groundless discrimination". It largely stems from the rising McCarthyism in the political circle of the US today-Being an ethnic Chinese is enough for those working in key research and development posts to be suspected of stealing US know-how.

Even if these targeted Chinese-Americans are proven innocent at last, the investigations, which is nothing but a kind of political persecution, have already damaged their reputations and disturbed their normal work.

If the state machine indiscriminately makes those of a particular ethnicity feel imperiled under the excuse of protecting national security, then national security has already become "an imperial sword".

That is what Washington is doing to Chinese-American talents, in a repeat of what Russian and Japanese scientists experienced.

The universities and institutes should be the guardians of their scientists and researchers. But it is sad to see those employers, who often take pride in their independence and respect for truth, are in a hurry to dissociate themselves from their Chinese-American employees, even before any evidence is presented.

It is ridiculous that the FBI tries to find faults with their targets in their normal academic exchanges and cooperation with their Chinese partners, most of which are also participated in by their colleagues of other ethnicities, and permitted and encouraged by their US employers and even the US government, before the anti-China mood took hold of Washington.

Shutting its doors on Chinese-American scientists will only force more of them to leave the US, and deter more Chinese nationals from considering studying and working in the US, which will directly harm the US' national interests.

The US will necessarily fall on its own sword, if it insists on closing the door for cooperation and academic exchanges.