US-bound passengers have been banned from travelling with most electronic devices in their hand luggage on flights from several Middle Eastern and North African countries.
The reason for the ban was not immediately clear, but it will apply to passengers on non-stop flights to the US from international airports in Cairo in Egypt, Amman in Jordan, Kuwait City in Kuwait, Casablanca in Morocco, Doha in Qatar, Riyadh and Jeddah in Saudi Arabia, Istanbul in Turkey, and Abu Dhabi and Dubai in the United Arab Emirates.
Mobile phones and medical devices are excluded by the ban, but items such as laptops, iPads, cameras and most other electronics must be put in the traveller's checked baggage.
It is understood the indefinite ban was put in place as part of increased security measure is in response to an unspecified terrorism threat, and a US government official said the ban had been under consideration for several weeks.
In a tweet published on Monday, Royal Jordanian warned its passengers the ban will be "effective starting [on] March 21."
However the tweet appears to have been deleted, with the airliner now telling its customers "further updates will be announced soon".
Homeland Security Secretary John Kelly phoned politicians over the weekend to brief them on aviation security issues that have prompted the impending electronics ban, according to a congressional aide.
The ban would begin just before Wednesday's meeting of the US-led coalition against so-called Islamic State group held in Washington.
A number of officials from the country's affected by the electronics ban are expected to attend the State Department gathering.
It was unclear whether their travel plans were related to any increased worry about security threats.
Brian Jenkins, an aviation-security expert at the Rand Corp, said the nature of the security measure suggested it was driven by intelligence of a possible attack.
He added there could be concern about inadequate passenger screening or even conspiracies involving insiders, airport or airline employees, in some countries.
Another aviation-security expert, professor Jeffrey Price of Metropolitan State University of Denver, said there were disadvantages to having everyone put their electronics in checked baggage.
Thefts from baggage would sky-rocket, as when the UK tried a similar ban in 2006, he said, and some laptops have batteries that can catch fire, an event easier to detect in the cabin than in the cargo hold, he said.
Most major airports in the US have a computer tomography or CT scanner for checked baggage, which creates a detailed picture of a bag's contents.
CT scanners 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.