The Trump administration announced Friday that it has begun reexamining the refugee status of thousands of Minnesota residents, launching a sweeping review that subjects already-approved refugees to new background checks and interviews amid an expanded federal enforcement operation in the state.

U.S. Citizenship and Immigration Services said the effort began in mid-December and is initially focused on roughly 5,600 refugees in Minnesota who have not yet received lawful permanent resident status. The agency said the review has already led to referrals to Immigration and Customs Enforcement for suspected fraud and other criminal activity.