The Trump administration on Tuesday stopped scheduling new interviews for international students seeking visas to study in the United States as the State Department prepares for expanded social media screening of applicants, according to an internal cable seen by NBC News.

The directive was widely circulated to all U.S. diplomatic and consular posts abroad and signed by Secretary of State Marco Rubio. Politico first reported the cable.

The move is the Trump administration’s latest strike on higher education in general and international students in particular as it cuts financial support to Harvard and arrests visa-holding students from abroad.

The State Department said it would issue further guidance to consulates and embassies in the coming days.

It was unclear how the prospective students’ social media would be screened as part of the expanded vetting procedures. The public views and speech of international students have come under increased scrutiny during the Trump administration.

The visas of thousands of students at college campuses nationwide have been revoked in recent weeks by the Trump administration, which says it must protect U.S. citizens from immigrants who intend to commit terrorist attacks, threaten national security or espouse hateful ideology.

The future of foreign students at Harvard remains uncertain after the Trump administration banned their enrollment starting in the next school year.

Many universities nationwide have warned international students about traveling abroad this summer, fearing many will not be allowed to return.

The crackdown could also financially affect other universities with significant numbers of foreign students.