WASHINGTON — The U.S. government, citing unspecified threats, is barring passengers on nonstop, U.S.-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 early Tuesday morning and airlines will have until 3 a.m. EDT Saturday to implement them or face being barred from flying to the United States, 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 U.S.-based airlines have nonstop flights from those cities to the United States.

With the order affecting flights from predominantly Muslim nations, the ban may invite comparisons to Trump’s orders barring travel from several Muslim-majority-nations, which has been blocked by courts. Early in his candidacy, Trump had called on barring Muslims from entering the United States.

But the comparison has its limits. The travel ban was more severe, separating families and barring students from studying in the U.S.  The laptop ban is more of an inconvenience and its stated reason is to protect the very travelers who are affected by it. Still, it’s bound to annoy powerful business people and diplomats, and could affect the travel plans of wealthy tourists sought after by the U.S. travel industry.

Details of the electronics 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.