More than a million migrants who were allowed to enter the United States during the Biden administration may have their temporary stays revoked and be rapidly deported, according to an Immigration and Customs Enforcement document that became public Friday.

The Department of Homeland Security has empowered federal immigration officials to bypass protections for hundreds of thousands of migrants who entered the country legally through Biden administration programs and begin immediate and rapid deportations,

For weeks, lawyers and advocates, worried about President Donald Trump’s promised immigration crackdown, have been telling asylum seekers and migrants temporarily paroled into the United States to keep their documents with them at all times in case they are stopped by overzealous cops or immigration agents.

The U.S. Department of Homeland Security memo provides guidance for the use of a fast-track deportation process that the Trump administration reinstated earlier this week, suggesting officers focus on migrants who failed to request asylum within a one-year deadline after arriving in the U.

The Trump administration is powering ahead with efforts to ramp up immigration enforcement, opening up the possibility of targeting migrants who entered through Biden-era programs and invoking an obscure immigration statute to make it easier to deputize state and local law enforcement to arrest and detain immigrants in the U.

Many of the migrants under threat spent months waiting in Mexico, at migrant shelters or in rented rooms, in cities that are rife with cartel violence and kidnappings, in order to enter the US with permission.