A crackdown on foreign students is alarming college leaders, who say the Trump administration is using new tactics and vague justifications to push some students out of the country.

These are troubling times, and this situation is unlike any we have navigated before,” the university president said in a statement.

Some graduate students at the University of Kentucky have had their visas revoked, President Eli Capilouto said in a campus-wide message Friday afternoon. In his message, Capilouto wrote that the Department of Homeland Security notified UK that the department was revoking some F-1 student visas.

Neither university has identified the students who lost their visas, said what countries they are from, or revealed whether federal officials provided any explanation.

At least nine students between the University of Colorado and Colorado State University have had their visas revoked by the Department of Homeland Security, spokespeople for the schools have said.

Colorado State University said on Wednesday that an additional student had their visa revoked after several were revoked a day earlier. The Department of State acknowledged the move but won't say why they were revoked.

The university released few details, but the move comes amid the Trump administration's efforts to deport students involved in pro-Palestinian protests on college campuses.

A "small number of international graduate students" at the University of Kentucky have had their student visas or status revoked, officials said.