The State Department said Thursday it is reviewing more than 55 million people who have valid US visas for any violations that could lead to deportation, part of a growing crackdown on foreigners who are permitted to be in the country, reports AP.

In a written answer to a question from AP, the State Department said all US visa holders, which can include tourists from many countries, are subject to “continuous vetting,” with an eye toward any indication they could be ineligible for permission to enter or stay in the United States.

Should such information be found, the visa will be revoked, and if the visa holder is in the US, he or she would be subject to deportation.

The State Department said it was looking for indicators of ineligibility, including people staying past the authorized timeframe outlined in a visa, criminal activity, threats to public safety, engaging in any form of terrorist activity, or providing support to a terrorist organization.

“As part of the [President Donald] Trump Administration’s commitment to protect U.S. national security and public safety, since Inauguration Day the State Department has revoked more than twice as many visas, including nearly four times as many student visas, as during the same time period last year,” the State Department said.