The Department of Homeland Security "might" prohibit laptops as carry-on items for all international flights in and out of the United States, Homeland Security Secretary John Kelly said Sunday in an interview with Chris Wallace on Fox News Sunday.

The United States being a "free and open society" is "one of our vulnerabilities," Kelly said. "There's a real threat — numerous threats against aviation. That's really the thing that they're 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." Electronic carry-ons are already limited for flights from 10 Muslim-majority countries in the Mideast and North Africa.

Kelly also said he would "likely" expand nationwide a new TSA policy of requiring passengers to more substantially unpack their carry-on bags at the checkpoint, separating food and paper items into different bins. A 2015 DHS investigation found TSA officers failed to detect 95 percent of explosives and weapons passed through airport security in an internal test. Terrorism experts say the long lines caused by slow TSA checkpoints are themselves a security risk.