The move, which could expose unregistered migrants to criminal prosecution, represents a drastic escalation of the administration’s efforts to push millions of immigrants to leave on their own.

The move applies to immigrants over the age of 13 who are in the U.S. unlawfully and who have not submitted fingerprints or registered with the federal government.

The Trump administration is creating a registry for all people who are in the U.S. illegally, and those who don’t self-report could face fines or prosecution.

But lawyers and immigrant advocates warned that the administration’s plan was on shaky legal ground and that some immigrants may be afraid to comply.

Trump Administration wants all immigrants who do not have legal status in the country to provide personal information and fingerprints, including children. Immigrant rights group raise alarms.

Immigrants in the U.S. illegally who fail to register with the federal government could face significant fines, potential imprisonment or both, according to a directive issued by the Department of Homeland Security on Tuesday.