More than 20,000 undocumented immigrants were arrested during the first month Donald Trump was president, according to the Department of Homeland Security.

Everyone 14 or older and in the U.S. without legal status will be required to give the federal government fingerprints and provide an address. It’s another escalation of the administration’s

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.