Fulfilling his election pledge to use “extreme vetting” to prevent ISIS militants from entering the country, Trump said the US only sought to admit those who would “love deeply” the American people.
He said: "I'm establishing new vetting measures to keep radical Islamic terrorists out of the United States of America. Don't want them here.
"We only want to admit those into our country who will support our country and love deeply our people.”
The details of the order are still unknown, but are expected to be announced at the White House later this evening.
Trump has said separately that Syrian Christians will take priority when it comes to applying for refugee status.
The President said the US only wanted migrants who would support the country.
Mr Trump has previously called for a "complete and total shutdown" of Muslims entering the US.
In an interview with the Christian Broadcasting Network, he said it was “almost impossible” for Syrian Christians to successfully claim asylum.
He said: "If you were a Muslim you could come in, but if you were a Christian, it was almost impossible and the reason that was so unfair, everybody was persecuted in all fairness, but they were chopping off the heads of everybody but more so the Christians.”
“And I thought it was very, very unfair. So we are going to help them."
The President made defeating ISIS one of the pillars of his campaign.
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Fri, January 27, 2017
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Trump speaks briefly to reporters as he arrives aboard Air Force One at Joint Base Andrews
But legal experts have argued over whether Mr Trump’s position could be challenged as a violation of the US constitution.
Stephen Legomsky, a former Chief Counsel at US Citizenship and Immigration Services in the Obama administration, said prioritising Christians was unconstitutional.
He said: "If they are thinking about an exception for Christians, in almost any other legal context discriminating in favour of one religion and against another religion could violate the constitution.”
But Peter Spiro, a professor at Temple University School of Law, said the President’s move would likely be constitutional because America’s political system allows considerable deference when it comes to asylum decisions.
He said: "It's a completely plausible prioritisation, to the extent this group is actually being persecuted.”