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."
What's changed from the Obama era?
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.
What's in the new orders?
The two memos released on Tuesday by the agency also allow Border Patrol and Immigration and Customs Enforcement to deport people immediately.
During Mr Obama's presidency, expedited removals were applied to people who had been in the country for no more than 14 days and were within 100 miles of the border.
Under the new guidance, agents can expedite deportations for undocumented immigrants who are unable to prove they have been in the country for more than two years, located anywhere in the US.
Some of the new priorities include:
- Expanding deportations to undocumented immigrants who have been charged with a crime, misrepresented themselves, pose a risk to public safety, or "have abused any program related to receipt of public benefits" - effectively allowing agents to arrest any illegal immigrant they encounter
- Ending US policy to release those caught on the border and instead placing them into detention centres until their cases are resolved
- Calling for authorities to prosecute parents who help smuggle their children into the country
- Allowing plans to begin on an expansion of the border wall along the US southern border
The DHS plans to hire an extra 10,000 agents for Immigration and Customs Enforcement and 5,000 more border patrol officers to enforce the new guidance.
Homeland Security Secretary John Kelly wrote in one of the memos: "The surge of illegal immigration at the southern border has overwhelmed federal agencies and resources and has created a significant national security vulnerability to the United States."
Mr Kelly's memo also includes instructions to enforce an existing provision of the US Immigration and Nationality Act that allows authorities to send some people caught illegally at the border back to Mexico, regardless of where they are from.
It is unclear whether the US has authority to force Mexico to accept foreigners.
Where's this guidance come from?
It is a blueprint to implement executive orders that Mr Trump signed on 25 January, days after taking office.
The new guidelines did not explain how Mr Trump's border wall would be funded and where undocumented immigrants apprehended in the crackdown would be detained.
The memos instruct agents to use "all available resources to expand their detention capabilities and capacities", but Congress would probably need to allocate money to build new detention centres.