The United States and United Kingdom have banned laptops, tablets and other electronic devices in the cabins of some flights from airlines operating in parts of North Africa and the Middle East.

The U.S. ban, which affects devices larger than a cellphone ― including cameras, DVD players and electronic games ― went into effect Tuesday morning, senior Trump administration officials said in a conference call with reporters.

Federal officials, requesting anonymity, said intensifying threats from terrorist groups against commercial airlines and airports prompted the new rules. Officials from the Departments of Homeland Security and Transportation imposed the change, officials said in the conference call.

“Evaluated intelligence indicates that terrorist groups continue to target commercial aviation, to include smuggling explosive devices in various consumer items,” said a DHS fact sheet released Tuesday. “The record of terrorist attempts to destroy aircraft in flight is longstanding and well-known.”

The rules affect passengers on direct flights to the U.S. from 10 airports in Egypt, Jordan, Kuwait, Qatar, Morocco, Saudi Arabia, Turkey and the United Arab Emirates.

These airports were chosen “based on the current threat picture,” the DHS sheet said.

White House press secretary Sean Spicer on Tuesday declined to provide additional information about the cause for precaution.

“As you can imagine, I can’t talk about the intelligence that we have,” Spicer told reporters. “I can just tell you that the steps that are being taken are commensurate with the intelligence we have.”

The affected airlines are all foreign carriers. Egypt Air, Emirates, Etihad Airways, Kuwait Airways, Qatar Airways, Royal Air Maroc, Royal Jordanian, Saudia and Turkish Airlines have 96 hours to implement the change, officials said.

Passengers on the roughly 50 flights per day affected by the change can put the banned devices in checked baggage.

The United Kingdom implemented a similar ban Tuesday ― it encompasses some U.K. airlines in addition to foreign airlines and only applies to flights from six countries.

There’s no specific end date to the ban, DHS added. It will remain in place “until the threat changes.”

Authorities referred to the recent downings of commercial planes by terrorists and the attack at Istanbul Ataturk Airport that killed 45 people last June in justifying the electronics ban. They declined to say whether they’d uncovered new information that led to the tightened rules.

Canada’s transportation minister, Marc Garneau, said Tuesday that he’s reviewing the electronics bans, but gave no indication of whether such a policy would be adopted by his country’s government.

One security expert said it’s possible the departments behind the ban are concerned with the size of an electronic device rather than how much information is stored on it.

“My assumption would be that if there’s a security basis for the ban, there’s some new means of masking explosives in a device that can’t be detected by X-rays,” Jake Laperruque, senior counsel at The Constitution Project, told The Huffington Post. “I can have a phone that can hold 10 times more information than a laptop. ... This seems to be a ban based on size of a device and implies that it has something to do with hardware and what you can put into hardware.”

The revision supersedes Federal Aviation Administration warning that lithium batteries in many electronics posed a fire risk when stored with checked baggage in a plane’s hold.

A tweet from Royal Jordanian airlines created confusion Monday when it was sent before the security measure was announced.

The company said that starting March 21, passengers could no longer bring cameras, DVD players and electronic games with their carry-on items and that such items must be checked on flights to and from New York, Chicago, Detroit and Montreal.

Cellphones and medical devices would still be permitted, Royal Jordanian said.

The tweet was later deleted.

Officials on the conference call said they had no complaint with how Royal Jordanian informed its customers of the electronics rules.

Saudia also commented on the new measure in a tweet, advising customers about which devices were banned.

This article has been updated throughout as more details have become available.

CORRECTION: An earlier version of this article mistakenly stated the ban applies to flights to and from the United States. The rule for electronics, however, only affects flights on the listed airlines bound for the U.S. from the affected North African and Middle Eastern airports.