The nation's major airlines will start randomly checking people's electronic devices for explosives prior to boarding in response to a U.S. counterterrorism request, airport sources said.

The new measure is likely begin on Tuesday at Tokyo's Haneda airport, Narita airport and five airports in Hokkaido, Sendai, Chubu, Kansai and Fukuoka that have direct flights to the United States.

The added layer of security could cause delays as many passengers may be unaware of the change.

The random screenings will cover devices including computers, tablets, e-readers and cameras, the sources said. Phones will be exempt.

Security personnel will now use explosives detectors at the request of the U.S. government.

The checks will likely be conducted at the departure gates rather than the security checkpoints, because the United States is calling for passengers to be segregated from those boarding other flights once screened.

The U.S. Department of Homeland Security has expressed concern that terrorists are improving their ability to plant explosives in electronic devices. It claims that an explosives-laden laptop was used in a terrorism case in Somalia in February 2016. The enhanced measures for U.S.-bound flights were unveiled in late June.