New US President Donald Trump’s travel ban on travellers from seven Muslim-majority countries was a major win for his own political ambitions, but it is also proving unpopular with many Americans.
The move to bar travellers from Iran, Libya, Somalia, Sudan, Syria, Yemen and Somalia is the biggest policy win for Mr Trump and his allies in the administration.
The White House says it is aimed at keeping out terrorists, foreign spies and the spread of Ebola.
The ban was implemented on Sunday, but has already caused widespread confusion and protests at airports and other points of entry.
Critics say the travel ban is a thinly veiled attempt to discriminate against Muslims and is likely to have a chilling effect on future travel.
The Trump administration says it has been successful in its goal of preventing terrorism and stopping terrorist infiltration of the United States, and says the ban will keep foreign travellers out.
In a statement, Mr Trump said the travel restrictions were necessary to protect the American people from terrorism and a potential pandemic.
The decision by the Trump administration to restrict the travel of nationals of Iran, Iraq, Libya and Somalia from entering the US, the world’s largest Muslim-dominated nation, has led to widespread condemnation from human rights organisations.
Iran’s supreme leader, Ayatollah Ali Khamenei, said the move was aimed at preventing a nuclear deal with world powers.
“It is an absolute disaster for America, for our country and for the world,” he said in a televised address.
“This is a clear sign that the Trump Administration is determined to put an end to the talks on Iran’s nuclear programme, as it has done for the past five years,” he added.
“The Trump Administration must know that the Iranian people are watching this.”
The US State Department has said the ban has been approved by the White House and Congress.
Iran and other Muslim countries have been subject to a series of US sanctions for their involvement in the Islamic State militant group and other foreign threats.
The Iranian government has said it does not seek confrontation with the US and that its citizens are safe in the US.
Iran is not a state sponsor of terrorism.
Its ambassador to the US has described the travel restriction as a “misguided and ill-advised” decision.
“Iran has never tried to provoke the US,” Zarif Isfahani said.
“We have always maintained diplomatic relations with the USA.
And we hope that they will reciprocate this respect,” he told reporters on Saturday.
The US has said that Iran will not face sanctions if it implements the ban, but the Iranian government is expected to file a lawsuit against the US in the coming days.
A spokesperson for the State Department, Jen Psaki, said Mr Trump’s decision “was taken in accordance with the law, the constitution and international law, and it will continue to apply”.
“The president has said he is not interested in a war with Iran,” Ms Psaki added.
Mr Trump signed a revised travel ban in April that bars travellers from Iraq, Iran, Syria and Yemen from entering for 90 days, but also bans Iranians from travelling to the United Arab Emirates for 90 more days.
Iranians have also protested against the ban.
A protest by Iranian students was held in New York on Saturday against the new travel restrictions.
In another sign of tensions in the Middle East, a Turkish cleric was arrested for alleged involvement in a plan to bomb a gas station in Istanbul.
Iranian authorities have detained several people who were reportedly planning attacks on gas stations in Istanbul, where a planned rally in support of the government has been postponed.