Donald Trump is expected to move as early as today to stem the flow of all refugees to the US and bar those fleeing war-torn Syria indefinitely, as Mexico’s president was said to be considering calling off his visit to Washington.
The new US president moved aggressively to tighten America’s immigration controls on Wednesday, signing executive actions to jump-start construction of his promised US-Mexico border wall and cut government grants for “sanctuary cities”.
“Beginning today the United States of America gets back control of its borders,” Mr Trump declared during a visit to the Department of Homeland Security.
“We are going to save lives on both sides of the border.”
The actions, less than a week into his presidency, were cheered by Republicans allies in Congress, condemned by immigration advocates and triggered immediate new tension with the Mexican government.
“I regret and reject the decision of the US to build the wall,” President Enrique Pena Nieto said in a nationally televised address.
“I have said time and again, Mexico will not pay for any wall.”
He did not directly mention whether he would make the trip to Washington on 31 January, but said he would await reports from the top-level team of Mexican officials currently meeting with Trump staff in Washington.
Later, a senior official said Mr Pena Nieto was “considering” cancelling the visit.
Mr Trump’s upcoming order is also expected to suspend issuing visas for people from several predominantly Muslim countries - Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen - for at least 30 days, according to a draft executive order obtained by The Associated Press news agency.
He is unveiling his immigration plans at a time when detentions at the southern border are down significantly from levels seen in the late 1990s and early 2000s - the arrest tally last year was the fifth-lowest since 1972.
Deportations of people living in the US illegally increased under Barack Obama, but Republicans criticised him for setting prosecution guidelines that spared some groups from the threat of ejection, including those brought to the US illegally as children.
As a candidate, Mr Trump tapped into the immigration concerns of some Americans who worry both about a loss of economic opportunities and the threat of criminals and terrorists entering the country.
His call for a border wall was among his most popular proposals with supporters, who often broke out in chants of “build that wall” during rallies.
Immigration advocates and others condemned Mr Trump’s actions.
Omar Jadwat, director of the American Civil Liberties Union’s Immigrants’ Rights Project, said the president’s desire to construct a border wall was “driven by racial and ethnic bias that disgraces America’s proud tradition of protecting vulnerable migrants”.
How Mr Trump plans to pay for the wall project is unclear.
While he has repeatedly promised that Mexico will foot the bill, US taxpayers are expected to cover the initial costs and the new administration has said nothing about how it might compel Mexico to pay back the money.
In an interview with ABC News on Wednesday, Mr Trump said: “There will be a payment; it will be in a form, perhaps a complicated form.”
In an interview on MSNBC, House of Representatives speaker Paul Ryan said Congress would work with Mr Trump on the up-front financing for the wall.
Asked about estimates that the project could cost $8-14 billion (£6-£11bn), Mr Ryan said: “That’s about right.”
To build the wall, the president is relying on a 2006 law that authorised several hundred miles of fencing along the 2,000-mile frontier.
That bill led to the construction of about 700 miles of various kinds of fencing designed to block both vehicles and pedestrians.
The president’s orders also call for hiring 5,000 additional border patrol agents and 10,000 more immigration officers, subject to the approval of congressional funding.
Mr Trump also moved to end what Republicans have labelled a catch-and-release system at the border, where, some caught crossing illegally are released and given notices to report back to immigration officials at a later date.
The crackdown on sanctuary cities - areas that do not co-operate with immigration authorities - could cost individual jurisdictions millions of dollars.
But the administration may face legal challenges, given that some federal courts have found that cities or counties cannot hold immigrants beyond their jail terms or deny them bail based only on a request from immigration authorities.
Some of the nation’s largest metropolitan areas, including New York, Los Angeles and Chicago, are considered sanctuary cities.