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Travelers flying into the United States from certain overseas airports will be required to turn on their cellphones and other electronic devices for the preflight scanning and inspection, the Transport Security Administration (TSA) announced yesterday (July 6).

People with a unpowered device will not be allowed to board their flights, the TSA said in an online posting, and those passengers "may also undergo additional screening."

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The increased security measure is a response to new intelligence about possible terrorist plots, a DHS official told CNN, adding that the affected airports are mostly located in the Middle East and Europe. The airports were not named.

The new regulation comes from a directive by Secretary of Homeland Security Jeh Johnson.

"DHS [Department of Homeland Security] continually assesses the global threat environment and reevaluates the measures we take to promote aviation security," Johnson wrote in a statement on the DHS's website last week.

Neither Johnson's statement nor the TSA announcement yesterday specified what other kinds of electronic devices would be affected. TSA agents have occasionally asked flyers to power up their laptops, but the practice does not appear to be official policy.

Though this increased inspection is required in order to board your flight, U.S. citizens still do not need to divulge their device passcodes or encryption codes during border searches.

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