Homeland Security Secretary John Kelly John Francis KellyMORE said on Sunday that he is weighing a ban on laptops from the cabins of all international flights, and "likely will" implement tougher screening of carry-on items at airports.

"There’s a real threat. Numerous threats against aviation, that's really the thing that they are obsessed with, the terrorists, the idea of knocking down an airplane in flight, particularly if it’s a U.S. carrier, particularly if it's full of mostly U.S. folks, people. It's real," he said on "Fox News Sunday."

Kelly announced a decision in March to ban laptops from the passenger cabins of international flights originating from 10 cities in the Middle East and North Africa amid heightened concerns of terrorist attacks. Under than ban, laptops must be kept in checked luggage.

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Asked whether he would expand that ban to include all international flights into and out of the U.S., Kelly responded that he "might."

Kelly also indicated that he was likely to approve heightened screening measures for carry-on items, which would require passengers to unpack their carry-on bags and sort the items into separate bins. The Transportation Security Administration (TSA) is currently testing the screening measure.

Kelly said that airline passengers' tendencies to overpack their carry-on bags to avoid checked-bag fees has made it increasingly difficult for TSA agents to screen the items.

"The more you stuff in there, the less the TSA professionals that are looking at what's in those bags through the monitors, they can't tell what's in the bags anymore," he said.