Britain is imposing enhanced security measures will authorize security staff to require any airline traveler — not just those bound for the United States — to power on electronic devices to guard against hidden explosives.
Travelers going to and from Britain on Wednesday faced the new rules.
Travelers from France to the United States began undergoing checks Tuesday and the national airport security agency says the security measures were expected to last through the summer.
Germany says travelers to the United States should expect checks, but did not specify when they would start.
American intelligence officials are worried about new al-Qaida efforts to produce a bomb. Powering up computers or phones allows screeners to see that they are working and that explosives have not been substituted for batteries.