But as sensational as Butina’s story really is, the fact that she entered the country on a student visa is not at all surprising.

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In the days immediately after 9/11, when I was the deputy associate director of Central Intelligence for Homeland Security, it came to our attention that the United States had precious little information on foreign students. We were hard-pressed to tell whether those granted student visas showed up for classes, whether they switched majors from music to nuclear physics, or what information they might be sending home along with their graduation photos.

Although the government is now much better at knowing the whereabouts of these students, there is no systematic effort to monitor what intelligence-related information, if any, they ship back home. But there is reason to fear that some number of them assist not only their government’s intelligence services but also, especially in the case of China, multinational corporations actively engaged in industrial espionage.

I don’t mean to encourage some xenophobic reaction; I certainly don’t believe the nation should shun foreign students. On the contrary, the presence of these young people from all around the world makes America stronger. These students are important for our economy and the diversity of our academic communities.

That said, we must adopt a more realistic understanding of the counterintelligence implications of having so many foreign students on our soil. In 2017, an estimated 1.1 million international students were in the United States. China was by far the most common country of origin, with 33 percent of that number. Saudi Arabia has more than 50,000 students in the United States, and Russia slightly more than 5,500.

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In my nearly three decades of service in the CIA—including, at one point, as the deputy chief of the East Asia division in the Directorate of Operations—I came to know that Chinese security officials meet with many of their students before they go abroad to study, and in certain cases debrief them on return. While the Russians may not be quite as meticulous at weaponizing their young scholars, it is clear that a number of these students are amateur talent scouts for the motherland’s intelligence services. I learned not only that foreign students from traditionally hostile countries studying in the United States spot and assess potential intelligence targets, but also that they are given laundry lists of research material and intellectual property that their handlers would like them to funnel back home. In addition, the student visitors are asked to keep an eye on their fellow citizens in the United States, reporting those who appear to have “gone native.”