CNN -

A very limited number of airline passengers flying in the United States will be asked to turn on electronic devices while going through airport checkpoints, in an expansion of a security protocol implemented last week at some overseas airports, a U.S. official tells CNN.

The new procedure will be used for travelers on the "Selectee List" -- who are already getting enhanced screening because they are on U.S. government watch lists, the official said.

The change was implemented domestically Tuesday, and was first reported Wednesday by NBC News.

The U.S. government last week required the stepped-up security measure at airports in Europe, the Middle East and Africa to address concerns that terrorist groups are looking for new ways to sneak explosives onto aircraft. The procedure helps assure that electronic devices haven't been modified to conceal an explosive.

The change expands the protocol to include a very limited number of people on domestic flights.

From a security perspective, travelers generally fall into one of three groups -- passengers in the Pre-Check program who have been pre-cleared by the TSA; general travelers; and "selectees," those on government watch lists. Selectees are already subjected to enhanced screening, typically pat-downs and a more thorough examination of carry-on luggage.

It is this third group that will be targeted by the change, the official said.

If a selectee's electronic device is not capable of being turned on, they will be given the option of continuing without the item or of not flying, the official said.