Passengers may be asked to power up their carry-on electronic devices as part of stepped up security measures, the US Transportation Security Administration announced Sunday.

The US Department of Homeland Security announced last week that increased security measures for certain airports with direct flights to the US would be implemented as part of global threat assessments.

On Sunday, TSA issued the following statement: “As the traveling public knows, all electronic devices are screened by security officers. During the security examination, officers may also ask that owners power up some devices, including cell phones. Powerless devices will not be permitted onboard the aircraft. The traveler may also undergo additional screening.

“TSA will continue to adjust security measures to ensure that travelers are guaranteed the highest levels of aviation security conducted as conveniently as possible.”

Affected airports have not been named, but major European hubs such as London Heathrow, Frankfurt and Paris Charles de Gaulle are believed to be among them. So far, there have been no reports of delays at security checkpoints, but Heathrow and Manchester have advised passengers to keep their electronic devices charged up and be prepared as these may be checked at the security entrance and/or the gate prior to boarding.

TSA and the US do not operate direct security at those airports, but all countries are complying with US government recommendations for increased security measures, which are believed to be the result of intelligence reports of a credible terrorist threat.