Harvard University reports having a total of 6,963 international students on campus, 1,047 of whom are undergraduates. This is out of a total of 30,391 students, 8,527 of whom are undergraduates. Harvard suggests that international students make up about 22.9% of the student body.
Harvard likes the $$$ for foreign tuition more than the safety of their US students.
We lavishly subsidize the higher ed industry. Figures like that make them look like ingrates.