A tourist who saw a US soldier run across the North Korean border said she first thought it was part of a TikTok stunt.
Private Second Class Travis T King was reportedly facing disciplinary action by the US military when he crossed into the secretive country, US officials said.
Sarah Leslie, from New Zealand, was in the same tour group as the 23-year-old soldier.
She said he left the group as their walk around the joint security area (JSA) of the 160-mile demilitarised zone (DMZ) separating North and South Korea was coming to an end.
“We had spent the morning looking at various things in the DMZ and in the afternoon we went into the JSA and were given a tour of the setup in that area, which is where North Korea and South Korea have held meetings,” she told Sky News.
“There’s a number of buildings that straddle the boundary – they are painted bright blue. We had a look around those buildings.
“Then we had left and we were sort of hanging around on the tarmac between those buildings and a larger building on the South Korean side.
“People weren’t really doing much, just taking photos and talking and that kind of thing. I noticed some guy running very, very fast towards the North Korean side.
“I thought it was some kind of stupid stunt that he was doing for TikTok or something like that. I thought that was an incredibly stupid thing to do in a place like that.
“He just didn’t slow down and didn’t stop. There were soldiers who had been supervising us – they yelled.
She continued: “They chased him, but he was going so fast and he was so close to the border that they couldn’t catch him.”
Other people on the tour group were “pretty confused” and ushered into a building on the South Korean side. They were taken to a place outside the joint security area “pretty quickly”.
“It was not something that I ever thought would happen. At the time I was quite scared.”
Ms Leslie said the soldier had behaved normally during the tour and had bought a hat at a souvenir shop nearby.
“I noticed that he seemed to be by himself, but there were a couple of other people who were by themselves as well. Most people were family, and friends, in a group.
“I did overhear someone else say that they sat near him or with him and he was very quiet,” she said.
Ms Leslie said she did not know if Mr King was a late addition to the tour but that she had to provide passport details four days beforehand.
Mr King’s mother told ABC News that she was shocked to hear her son was in North Korea and says she just “wants her son to come home“.
The soldier bolted into North Korea a day after he was supposed to travel to a base in the US.
He was scheduled to return to Fort Bliss, Texas, where he could have faced additional military discipline and discharge from the service.
He was escorted as far as customs but left the airport in South Korea before boarding his plane. It was not clear how he spent the hours until joining the tour and running across the border.
Reports in South Korea said he was released from prison there on 10 July after serving two months for assault.
Court documents show that in February a court fined King five million in South Korean won (£3,065) after he was convicted of assaulting an unidentified person and damaging a police vehicle in Seoul last October.
The ruling said King had also been accused of punching a 23-year-old man at a Seoul nightclub, though the court dismissed that charge because the victim didn’t want King to be punished.
It was unclear for how long North Korean authorities would hold the soldier but analysts said the incident could be valuable propaganda for the isolated country.
North Korea has remained silent about the detention of King, who is the first American held there in nearly five years.
The US bans its citizens from entering North Korea – the totalitarian state run by Kim Jong Un where millions live in hunger and poverty.
On Wednesday, North Korea test-fired two ballistic missiles into the sea in an apparent protest of the deployment of a US nuclear-armed submarine in South Korea for the first time in decades.