The Trump administration has issued tough guidelines to widen the net for deporting illegal immigrants from the US, and speed up their removal.
Undocumented immigrants arrested for traffic violations or shop-lifting will be targeted along with those convicted of more serious crimes.
The memos do not alter US immigration laws, but take a much tougher approach towards enforcing existing measures.
There are an estimated 11 million illegal immigrants in the US.
White House Press Secretary Sean Spicer said on Tuesday the new guidelines would not usher in mass deportations, but were designed to empower agents to enforce laws already on the books.
"The president wanted to take the shackles off individuals in these agencies," Mr Spicer said.
"The message from this White House and the Department of Homeland Security is that those people who are in this country, who pose a threat to our safety, or who have committed a crime, will be the first to go."Dreamers
The Department of Homeland Security's (DHS) new blueprint leaves in place Obama-era protections for immigrants who entered the US illegally as children, affecting about 750,000 young people known as Dreamers.
But it expands the more restricted guidance issued under the previous administration, which focused its policy on immigrants convicted of serious crimes, threats to national security or those who had recently crossed the border.
Donald Trump's immigration order marks a sharp break with those Obama-era policies. Instead - according to the Department of Homeland Security implementation memos - the Trump administration essentially will "prioritise" the deportation of almost all undocumented immigrants, everywhere.
The Homeland Security Department's list of prioritised "removable aliens" is so broad as to include just about every class of undocumented immigrant - with only a carve-out for individuals who entered the US as children.
All this will require more money and manpower - and the Trump administration is going to ask Congress for the former and go on a hiring spree to address the latter. Local and state law-enforcement officials will also be allowed to arrest unauthorised immigrants.
While Mr Obama aggressively enforced immigration law and ramped up deportations in some areas and at some times, there were notable instances where he de-emphasised action. In the Trump era immigration authorities are now being given the power to make a sea-to-sea, border-to-border push.