U.S. universities used to admit students from overseas so they could learn about American values and the virtues of our political system and bring that knowledge back to their home countries. We were exporting democracy and freedom, one student at a time.

It’s the other way around now. American students at our top universities are being exposed to a critical mass of foreign students, learning about their values and political systems, and then incorporating these perspectives into our political culture.

U.S. universities used to admit a small number of international students, hovering between 1% and 2% of total enrollment from the end of World War II until 1977. Since then, the percentage of foreign students has almost tripled, on average. At our leading universities, the share of students from abroad makes up about a third of their enrollment.

It’s often even higher at Ivy League universities. Almost 40% of their students come from overseas if you count those who participate in the Optional Practical Training program during the year after completing their degrees. Even if you exclude OPT student visa holders, who often remain an extra year at universities as researchers or instructors in their fields of study, 27% of Ivy League student enrollment consists of international students.

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Columbia University’s foreign students make up between 40% and 67% of its enrollment, depending on whether OPT students are counted. At the University of Pennsylvania, that figure is between 25% and 37%. At Harvard, it’s between 25% and 34%. Among the top 25 national universities identified by U.S. News rankings, the average foreign enrollment stands at 21% or 31%, depending on whether OPT students are included.

The wave of campus protests following the Oct. 7 attack by Hamas helps illustrate the consequences of this sea change. Chanting about the need to globalize the intifada or “free Palestine” “from the river to the sea,” removing 6 million Jews from Israel through death or expulsion, seems like a perfectly normal thing to do in many of these students’ home countries.

Through their influence, American students are learning how to wear keffiyehs and repeat genocidal slogans. Educational exchange is working, just not in the direction that American policymakers imagined when they created visa programs for international students.

It is telling that the universities with the most radical protests are also among those with the largest international enrollments. Columbia, the Massachusetts Institute of Technology, Harvard, Penn, Northwestern, Chicago, and Stanford all have over 30% foreign enrollments, including OPT students.

By contrast, the University of Mississippi, where counterprotesters sang the national anthem in response to Hamas supporters, only has 3% of its enrollment from abroad. At the University of North Carolina, where fraternity members rescued an American flag from being replaced by the Palestinian one, about 10% of students are international.

Using data from Harvard’s Crowd Counting Consortium, we find that among universities with at least 1,000 international students, those in the top quintile of foreign enrollment have had more than twice as many pro-Palestinian protests as universities in the bottom quintile. Campus outbursts increasingly resemble those abroad because they are increasingly led by the same people.

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Universities have rapidly increased foreign enrollments because foreign students compensate for declining domestic student populations and tend to be quite lucrative, typically paying full tuition and bringing with them generous donations and grants from wealthy foreign governments and people. The desire to expand foreign enrollments is so strong that MIT publicly announced its reluctance to discipline rule-breaking foreign student protesters for fear that their suspension might cause them to be deported.

As leading U.S. universities train more international students, they also have increased the rate at which they hire foreign faculty. These universities increasingly view themselves as global institutions, without particular obligations to the country that hosts and largely subsidizes their activities. So it’s no surprise to find faculty joining radical protests to agitate for the anti-American views they push in the classroom.

Of course, radical home-grown students have been promoting hostility toward America for many decades. The difference is that their efforts are greatly amplified by foreign reinforcements, preventing their fringe perspectives from being easily dismissed and ignored.

It is well past time for American policymakers to remind U.S. universities about where they are located and who is footing the bill for their excesses. These are American institutions, benefitting from U.S. taxpayers’ largesse, and they need to train the future American elite who will run our government and corporations.

If they can’t serve American purposes, they need to be cut off from American taxpayer subsidies. And maybe some should consider relocating abroad, given that they may feel more at home in the countries whose interests they increasingly serve.