People with ties to American universities, most of whom have shown support for pro-Palestinian causes, have been detained in the Trump administration’s crackdown on immigrants.

The administration has cited a rarely used statute allowing the secretary of state to revoke visas for noncitizens deemed a threat to foreign policy interests.

U.S. immigration officials detained Turkish student Rumeysa Ozturk amid a crackdown on pro-Palestinian activism. Her arrest sparked protests, while critics argue the move suppresses free speech and targets foreign students in academia.