A 23-year-old U.S. soldier crossed into North Korea on Tuesday “willfully and without authorization,” reports indicate. Travis King was on a tour when he took tourists by surprise and ran across the border. He is believed to currently be in the custody of North Korean armed forces, although Pyongyang has not yet responded to attempted contact made by U.S. officials.

King was a Private 2nd Class and had been a cavalry scout with the U.S. Army since January 2021, according to NPR. The soldier had been stationed in South Korea and was scheduled to be flown to the U.S. to face military disciplinary action. King recently served two months in prison for punching a South Korean national in a club last September. He was fined 5 million won ($3,942) for causing public damage and being uncooperative with police during his arrest, according to the AP.

King was released to U.S. officials a week ago and was being escorted to an airport outside of Seoul where he was to board a plane for Fort Bliss, Texas, reported CBS. The 23-year-old American reportedly managed to evade officials while at airport security. An airport official told The Korea Times that King had said his passport was missing as an excuse not to get on the flight.

King wore civilian clothes — jeans and a T-shirt — and joined a group of 43 tourists visiting the Demilitarized Zone between North and South Korea. He sprinted across the border before anyone had time to respond.

Sarah Leslie, a woman present during the tour, said he laughed out loud before bolting off, according to NPR. She shared that she had to submit her passport before taking part in the tour, which usually takes three days of planning because of security measures.

“I’m absolutely foremost concerned about the welfare of our troop,” Defense Secretary Lloyd Austin said in a press conference.

King’s family said they were shocked to hear the news and that defecting was “out of his character.” 

“I’ve never seen him get down like that, ever. Something’s going on. This is not his personality,” his uncle Myron Gates told NBC News.

His family added King was grieving the loss of his young cousin, The Independent reported.

“I can’t see Travis doing anything like that,” his mother, Claudine Gates, told ABC News. “I’m so proud of him. I just want him to come home, come back to America,” she added.

It isn’t the first time an American has been detained by North Korea. In 2016, U.S. college student Otto Warmbier was held for over a year after being accused of taking a poster from his hotel. Warmbier was released to U.S. officials while in a coma and died days after returning to the United States.

North Korea is known to be one of the most closed off military powers in the world. It is led by Kim Jong Un, and is known for practicing repression against its own population, according to Human Rights Watch. It routinely fires ballistic missiles in order to apply political pressure toward the U.S. and its allies.