President Donald Trump has signed a new executive order placing a 90-day ban on people from six mainly Muslim nations.
Iraq has been removed from the list of countries contained in the previous seven-nation order, while people with valid visas will be allowed to enter the US.
The measure, which includes a 120-day ban on all refugees, takes effect on 16 March to limit travel disruption.
The previous order, which was blocked by a federal court, sparked confusion at airports and mass protests.
US Secretary of State, Rex Tillerson, said the order is meant to “eliminate vulnerabilities that radical Islamic terrorists can and will exploit for destructive ends”.
The top US diplomat joined Attorney General Jeff Sessions and Homeland Security Secretary John Kelly at a news conference on Monday to discuss the new directive.
According to the FBI, more than 300 people who entered the US as refugees are under investigation for potential terrorism-related offences, Sessions said.
“Like every nation, the United States has a right to control who enters our country and to keep out those who would do us harm,” he said.
Citizens of Iran, Libya, Syria, Somalia, Sudan and Yemen, who were also on the initial ban list, will once more be subject to a 90-day travel ban.
Though the new order clearly states refugees already approved by the State Department will be allowed to enter, it also limits the number allowed in at 50,000 for the year.
The new directive also lifts a blanket ban on all Syrian refugees.
Green Card holders (legal permanent residents of the US) from the named countries will not be affected by the new order.
The Associated Press reports that the new order does not give priority to religious minorities, unlike the previous order.
Critics of the Trump administration had argued that was an unlawful policy showing preference to Christian refugees.
The new order is set to take effect on 16 March.
The 10 days’ advance notice may help to avoid some of the chaotic scenes at US airports that occurred on 27 January when the first executive order was announced without warning.
Travellers with valid visas who were in the air at the time of the order found themselves detained by border officials on arrival.
At the time, Trump defended the lack of notice, tweeting that “if the ban were announced with a one week notice, the ‘bad’ would rush into our country during that week”.
The delayed implementation will help the legal case, because one concern of the federal judges who refused to reinstate the original ban was that the justice department had failed to show that the executive order gave enough “notice and a hearing prior to restricting an individual’s ability to travel”.
Judges also found “no evidence that any alien from any of the countries named in the order” had committed a terrorist attack in the US, so the new ban may be subject to similar scrutiny.