(CNSNews.com) - North Korea isn't much of a threat right now, "as long as they're on the other side of the world without a missile and a nuclear weapon to deliver against the United States," Homeland Security Secretary John Kelly told CBS's "Face the Nation" on Sunday.
And while "homegrown terrorists" remain a concern, Kelly told host John Dickerson he has more pressing worries:
The other thing, John, that keeps me literally awake at night is the threat against aviation. We know that would be the Super Bowl for the terrorists to knock down an airplane in flight, particularly if it was full of Americans.
We have taken measures overseas to reduce that threat, but it's something I watch every day -- ask four or five time a day, because there are a number of plots that we're watching very, very closely. They're very sophisticated, they're very threatening, and the number-one thing in my mind is to protect the American people. So we'll do that.
Kelly later added that the aviation threat "is very real." He said if the terrorists are successful, "they're going to kill hundreds and hundreds of people in one fell swoop."
On the topic of homegrown terrorism, Kelly said, "I don't know how to stop that, I don't know how to detect that." He called it a "big problem."
"It is a big threat. Is it the number-one threat? I think it's the most common threat. Unfortunately, there are other similar-type terrorist threats that could come from outside the border. You know, the CIA, NSA, all the great men and women of DOD are doing a great job keeping them away from the homeland."
Kelly appealed to the public, repeating the familiar phrase, "if you see something, say something, whether you're a parent, a sibling, an imam.
"This extends, frankly, John, to white supremacists and that kind of terrorism as well. If you see a young man or a young woman going down that path where they're always on these kind of websites or saying things at church or in a mosque that are clearly disturbing, then tell someone about it so we can help that kid, young man or woman, before they break the law."