The Trump administration announced it is reviewing the visas of more than 55 million people for potential violations that could lead to revocation or deportation.

The State Department said all visa holders, including tourists, are subject to “continuous vetting” for overstays, criminal activity, or links to terrorism.

If issues are found, visas can be canceled and holders in the U.S. may face deportation, the Associated Press has reported.

The move expands the administration’s focus beyond undocumented immigrants to include legal visitors and raises questions about the practicality of reviewing people who may never return to the U.S.