US President Donald Trump has signed an order to strengthen the vetting of would-be immigrants or refugees and to keep "radical Islamic terrorists out of the United States of America."
At a ceremony at the Pentagon to swear in James Mattis as his secretary of defense, Mr Trump signed a decree entitled: "Protection of the nation from foreign terrorist entry into the United States."
"This is big stuff," he declared, to polite applause from gathered senior military brass.
The White House did not immediately make the wording of the decree public, but a draft text had been leaked to US media earlier in the week and was widely reported on.
According to this unconfirmed order, Mr Trump's decree suspends the entire US refugee resettlement program for at least 120 days while tough new vetting rules are established.
In addition, it specifically bars Syrian refugees from the United States indefinitely, or until the president himself decides that they no longer pose a threat.
Meanwhile, no visas will be issued for 30 days to travellers, whether would-be visitors or migrants, from seven mainly-Muslim countries: Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen.
Civil liberties groups and many counter terror experts had condemned the measures in advance, arguing that it is inhumane to lump the victims of conflict in with the extremists who threaten them.
But the suspension of the program stops short of a threat Mr Trump made during last year's race for the White House to halt all Muslim travel to the United States.
His supporters defend the measures as necessary to prevent supporters of Al-Qaeda or the so-called Islamic State group from infiltrating the US homeland disguised as refugees.
Trump orders 'great rebuilding' of US military
The US President also signed an order to begin what he called a "great rebuilding" of the US armed services, promising new aircraft, naval ships and more resources for the military.
"Our military strength will be questioned by no one, but neither will our dedication to peace. We do want peace," Mr Trump said in the Pentagon ceremony.
He predicted that Congress, which sets the expenditures for the government, will "be very happy to see" the White House's spending request for the military.
Earlier in the day, Mr Mattis ordered financial reviews of the costs of two major defense programs - the $400 billion F-35 fighter jet project and the $4 billion development of a new Air Force One presidential jet.
Mr Trump had complained that both were too costly.
