The Trump administration is moving to revoke visas from potentially hundreds of thousands of foreigners who have applied for or are seeking asylum in the United States.

The planned action would go after people who came to the US on temporary visas for reasons like tourism, education or business and then sought asylum to remain in the country long term. It comes as the Trump administration has aggressively sought to both prevent immigrants from coming to the US and to remove those who are already in the country.

A source familiar with the matter did not dispute that the action could impact 200,000 foreigners, as was first reported by the Associated Press, but said the revocations would not be done “in one fell swoop.”

“As the process will be ongoing, the number of revocations remains dynamic and will be done on a rolling basis,” State Department spokesperson Tommy Pigott said.

He said the State Department is coordinating with the Department of Homeland Security “to identify and revoke the nonimmigrant visas of foreigners who have come to the United States claiming to be short-term visitors, but then file for asylum to stay here permanently.”