Passengers flying to the United States or United Kingdom from specific countries in the Middle East and North Africa will not be allowed to bring carry-on electronic devices larger than a standard-size smartphone, representatives from both countries announced this week.

Citing “evaluated intelligence,” the U.S. Department of Homeland Security (DHS) stated in a press release that the new policy has been implemented indefinitely because terrorist groups continue to target commercial aviation.

Noting the downing of an airliner over Egypt in 2015, as well as armed attacks last year in Brussels and Istanbul, U.S. government agencies state they are concerned about terrorists using personal electronic devices (PEDs) as onboard explosives.

“We have reason to be concerned about attempts by terrorist groups to circumvent aviation security,” the DHS stated.

Restricted PEDs include:

Laptop and notebook computers
Tablet computing devices
Portable electronic games
Portable DVD players
Digital cameras

The PED ban applies only to flights departing from specified airports destined for the United States or the United Kingdom. The restrictions take effect immediately, but airlines have until Saturday to implement the new rule.

The countries with affected flights to the United States and/or United Kingdom are Egypt, Jordan, Lebanon, Morocco, Qatar, Saudi Arabia, United Arab Emirates, Tunisia and Turkey.

Currently, PED restrictions on U.S.-bound flights apply to these 10 specific airports:

Queen Alia International Airport (AMM)
Cairo International Airport (CAI)
Ataturk International Airport (IST)
King Abdul-Aziz International Airport (JED)
King Khalid International Airport (RUH)
Kuwait International Airport (KWI)
Mohammed V Airport (CMN)
Hamad International Airport (DOH)
Dubai International Airport (DXB)
Abu Dhabi International Airport (AUH)

According to USA Today, these airlines are impacted by the new PED policy: EgyptAir, Emirates, Etihad Airways, Kuwait Airways, Qatar Airways, Royal Air Maroc, Royal Jordanian, Saudia (Saudi Arabian Airlines), and Turkish Airlines.

In an online Q&A, the DHS left open the possibility that more airports and airlines could be added in the future “as threats change.”

Noting that size and shape of smartphones vary by brand, the DHS advised passengers impacted by the PED carry-on ban to consult with airline representatives if they have any questions about their devices.

“Passengers should pack large personal electronic devices in checked bags,” the DHS stated.