WASHINGTON, United States (AP) — The US government, citing unspecified threats, is barring passengers on nonstop, US-bound flights from eight mostly Middle Eastern and North African countries from bringing laptops, tablets, electronic games and other devices on board in carry-on bags.

Passengers flying to the United States from 10 airports will be allowed only cellphones and smartphones in the passenger cabins, senior Trump administration officials said. Larger electronic items must be checked.

The rules took effect Tuesday morning and airlines will have until 3:00 am EDT Saturday to implement them or face being barred from flying to the US, the officials said.

They said the decision was prompted by “evaluated intelligence” about ongoing potential threats to airplanes bound for the United States. The officials would not discuss the timing of the intelligence or if any particular terror group is thought to be planning an attack.

The Trump administration officials briefed reporters on condition that they not be identified publicly. That was despite President Donald Trump’s repeated insistence that anonymous sources should not be trusted.

The electronics ban affects flights from international airports in Amman, Jordan; Kuwait City, Kuwait; Cairo; Istanbul; Jeddah and Riyadh, Saudi Arabia; Casablanca, Morocco; Doha, Qatar; and Dubai and Abu Dhabi in the United Arab Emirates. About 50 flights a day, all on foreign carriers, will be impacted. The officials said no US-based airlines have nonstop flights from those cities to the United States.

Details of the ban were first disclosed by Royal Jordanian and the official news agency of Saudi Arabia.

In its statement, Royal Jordanian said the electronics ban would affect its flights to New York, Chicago, Detroit and Montreal.

Across the Atlantic early Tuesday, problems and confusion ensued.

Egyptian officials at the Cairo International Airport said they had not received any instructions on banning passengers from bringing laptops, iPads, cameras and some other electronics on board direct flights to the United States. The officials said a New York-bound EgyptAir flight departed and that passengers were allowed to take their laptops and other electronics on board in their carry-on luggage.

A spokesman for Royal Jordanian says the airliner has not yet started to enforce the new US regulation. Basel Kilani has told The Associated Press that the airline was still awaiting formal instructions from the relevant US departments, which could possibly come later on Tuesday.

However, the Mideast’s biggest airline is confirming that US-bound passengers will be prevented from carrying electronic gadgets aboard aircraft.

Dubai-based Emirates said Tuesday the ban takes effect on Saturday. That guidance differs from the information provided by senior Trump administration officials, who have said the ban is in place from Tuesday

Brian Jenkins, an aviation-security expert at the Rand Corp., said earlier that the nature of the security measure suggested that it was driven by intelligence of a possible attack. There could be concern about inadequate passenger screening or even conspiracies involving insiders — airport or airline employees — in some countries, he said.

Homeland Security Secretary John Kelly phoned lawmakers over the weekend to brief them on aviation security issues that have prompted the impending electronics ban, according a congressional aide briefed on the discussion. The aide was not authorized to speak publicly about the issue and spoke on the condition of anonymity.

The administration officials who briefed reporters about the ban said foreign officials were told about the impending order starting Sunday.

A US government official said such a ban has been considered for several weeks. The official spoke on the condition of anonymity to disclose the internal security discussions by the federal government.

The ban would begin just before Wednesday’s meeting of the US-led coalition against the Islamic State group in Washington. A number of top Arab officials were expected to attend the State Department gathering. It was unclear whether their travel plans were related to any increased worry about security threats.

Another aviation-security expert, Jeffrey Price, said there could be downsides to the policy.

“There would be a huge disadvantage to having everyone put their electronics in checked baggage,” said Price, a professor at Metropolitan State University of Denver. He said thefts from baggage would skyrocket, as when Britain tried a similar ban in 2006, and some laptops have batteries that can catch fire — an event easier to detect in the cabin than the hold.

Most major airports in the United States have a computer tomography or CT scanner for checked baggage, which creates a detailed picture of a bag’s contents. They can warn an operator of potentially dangerous material, and may provide better security than the X-ray machines used to screen passengers and their carry-on bags. All checked baggage must be screened for explosives.