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.

In one of his 10 inauguration day executive orders related to immigration, President Donald Trump initially outlined plans for creating a registry and required that Homeland Security “immediately announce and publicize information about the legal obligation of all previously unregistered aliens in the United States to comply.”