U.S. soldier Travis King has left military personnel and many others dumbfounded after he essentially defected into North Korea during a tour of the demilitarized zone bordering North and South Korea. 

King, who was recently released from a South Korean jail over an assault charge, was seen with a tour group getting a look at the DMZ before he sprinted across the border into North Korea and into North Korean custody. 

One witness from the tour group told NBC what she saw as King made a run for the North Korean border. “Suddenly I noticed a guy running—a guy dressed in black—running toward the North Korean side,” New Zealand national Sarah Leslie told NBC. “My first thought was, ‘What an absolute idiot.’ I assumed he was getting a mate to film it for some kind of TikTok stunt or something like that. But he just didn’t stop and he kept going. … He was going pretty fast.”

King was released from jail on July 10 after spending two months behind bars on charges of assault and property damage. He was seen at Incheon International Airport near Seoul but was supposed to board a flight back to the United States to face disciplinary action but said he forgot his travel docs. “He passed through all the security points up to the boarding gate but he told the airline staff that his passport was missing,” an Incheon Airport official told CNN. 

He is now considered to be a detainee of North Korea making him the first U.S. citizen to be detained by the country in five years. 

“I worry about him, frankly,” said Army Secretary Christine Wormuth during the Aspen Security Forum on Thursday. “I know everyone here remembers what happened when Otto Warmbier was taken into custody by the North Koreans and I think treated brutally. Obviously, you know, it makes me very, very concerned that Pvt. King is in the hands of the North Korean authorities, I worry about how they may treat him. So we want to get him back.”