The TSA said it will require some foreign airports to order passengers to turn on devices such as mobile phones. Any that do not power up will not be allowed on flights to the US, and those travellers may have to undergo additional screening.
The new rules come amid growing concern about the increased capability of al-Qaeda affiliates in Yemen and Syria, and the threat the foreign fighters of Syria pose to the home countries.
Sir Malcolm Rifkind, the chairman of the Intelligence and Security Committee, said jihadi extremists were deploying "devilish technical skill" to create ever more sophisticated devices to evade existing security measures.
He warned of the dangers of "complacency" among the public.