WASHINGTON • United States President Donald Trump has directed his administration to enforce the nation's immigration laws more aggressively, unleashing the full force of the federal government to find, arrest and deport those in the country illegally, regardless of whether they have committed serious crimes.

Documents released on Tuesday by the Department of Homeland Security revealed the broad scope of the President's ambitions: to publicise crimes by undocumented immigrants; strip such immigrants of privacy protections; enlist local police officers as enforcers; erect new detention facilities; discourage asylum seekers; and, ultimately, speed up deportations.

The new enforcement policies put into practice language that Mr Trump used on the campaign trail, vastly expanding the definition of "criminal aliens" and warning that such unauthorised immigrants "routinely victimise Americans", disregard the "rule of law and pose a threat" to people across the US.

Despite those assertions in the new documents, research shows lower levels of crime among immigrants than among native-born Americans.

The President's new immigration policies are likely to be welcomed by some law enforcement officials, who have called for a tougher crackdown on unauthorised immigrants, and by some Republicans in Congress who have argued that lax enforcement encourages a never-ending flow of unauthorised immigrants.

But taken together, the new policies are a rejection of the sometimes more restrained efforts by former presidents Barack Obama and George W. Bush and their predecessors, who sought to balance protecting the nation's borders with fiscal, logistical and humanitarian limits on the exercise of laws passed by Congress.

"The faithful execution of our immigration laws is best achieved by using all these statutory authorities to the greatest extent practicable," Mr John Kelly, the Secretary of Homeland Security, wrote in one of two memorandums released on Tuesday.

"Accordingly, department personnel shall make full use of these authorities."

The immediate impact of that shift is not yet fully known. Advocates for immigrants warned that the new border control and enforcement directives would create an atmosphere of fear that will likely drive those in the country illegally deeper into the shadows.

Administration officials said some of the new policies - like one seeking to send unauthorised border crossers from Central America to Mexico while they await deportation hearings - could take months to put in effect and might be limited in scope.

For now, so-called Dreamers, who were taken to the United States as young children, will not be targeted unless they commit crimes, officials said.

Mr Trump has not yet said where he will get the billions of dollars needed to pay for thousands of new border control agents, a network of detention facilities and a wall along the entire southern border with Mexico.

Lawyers and advocates for immigrants said the new policies could still be challenged in court.

Meanwhile, the Trump administration has sought to allay growing fears among immigrant communities, insisting that the measures are not intended to produce "mass deportations".

Federal officials said border patrol agents and immigration officers will use their expanded powers with care and discretion.

The number of people deported in 2015 was just over 333,000, the lowest since 2007, according to federal data. Statistics for last year are not publicly available.

NYTIMES, WASHINGTON POST