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

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.

The Trump administration is threatening to punish some immigrants in the U.S. illegally with criminal penalties, including jail time and fines, if they fail to sign up for a government registry.

The Department of Homeland Security (DHS) announced on Tuesday that any undocumented migrants above the age of 14 must provide the US government an address and their fingerprints. This is the latest move in the White House's effort to dramatically overhaul the US immigration system,

The Trump administration is creating a registry for all people who are in the United States illegally, and those who don't self-report could face fines or prosecution, immigration officials announced Tuesday.