DAVID GREENE, HOST:
Defense Secretary Jim Mattis flew into Seoul today, and he quickly then made an unannounced visit to the demilitarized zone separating North and South Korea. This was Mattis's first trip to the DMZ since taking over at the Pentagon. And it comes, of course, at a time of escalating tensions between the United States and North Korea following North Korea's series of nuclear tests. NPR's David Welna is traveling with the defense secretary and joins me from Seoul. Hi there, David.
DAVID WELNA, BYLINE: Hi, David.
GREENE: Quite a moment for a U.S. defense secretary to stare into North Korea, I would imagine.
WELNA: It was. You know, these trips to the DMZ have been made by a lot of top U.S. officials, including most of the recent presidents. And they've been fairly routine over the years, but, of course, now it's different because this Mattis trip to the DMZ took place under some pretty tense circumstances.
And while there were not any big incidents there, his appearance alongside South Korea's defense minister there I think was clearly meant to send a message to North Korea. Namely, don't you dare use your nuclear weapons or you'll be sorry you did.
GREENE: And just, David, I mean, most people have never been to this place. Can you just tell us what it's like?
WELNA: Well, you know, I'd never been there before. I heard a lot about it. And when I got there, it just was a little unreal. You know, here we had the defense chiefs of the U.S. and South Korea standing just a few feet away from a line of cement going across the pavement that looked just like a street curb. And it's actually the line that separates the North from the South.
And they both stood with their backs to North Korea as Mattis compared the North to what he called the peace-loving and free society of South Korea. Here's a bit of what he said.
(SOUNDBITE OF ARCHIVED BROADCAST)
JAMES MATTIS: Behind me to the north, an oppressive regime that shackles its people, denying their freedom, their welfare and their human dignity in pursuit of nuclear weapons and the means of delivery in order to threaten others with catastrophe.
GREENE: I mean, again, we've heard tougher language from President Trump and from people in the administration, but just to be delivering the message from that spot. Has the North reacted at all to Mattis's visit?
WELNA: Well, you know, Pyongyang had already denounced Mattis's visit as a rehearsal for a nuclear war. But even though this trip to the DMZ had not been announced beforehand, there were maybe a dozen stone-faced North Korean soldiers just across the line who seemed to know he was coming. Several of them marched right up to the line and stared at the two defense chiefs, one of them looking through what seemed to be binoculars, even though they were all practically within spitting distance of one another.
Just before Mattis and South Korea's defense minister left, they turned, and what looked like a gesture of defiance, they took just one look at the North Korean troops and their big stone fortress on the other side of the DMZ.
GREENE: Staring at you from - through binoculars but really close up. Maybe that's some sort of intimidation tactic. Let me just ask you, David. President Trump is going to South Korea next month. Is he going to go here to the DMZ?
WELNA: Well, you know, it's not clear. I think there's a lot of concern here about Trump provoking even more trouble with Pyongyang if he does go to the DMZ. And I think he may be concerned about his own security there. He hasn't yet said whether he'll go or not. He's kind of dithered when asked about it.
In the meantime, there are now three American aircraft carriers in the Western Pacific. And even though that's not unprecedented, it's being seen as one more sign that the Pentagon is taking no chances with what North Korean leader Kim Jong Un might do. Just this week, his foreign minister said that threats of an atmospheric test of a hydrogen bomb should be taken literally.
GREENE: NPR's David Welna in Seoul traveling with the defense secretary, Jim Mattis. Thanks, David.
WELNA: You're quite welcome, David.