CNN  — 

Just one day before crossing into North Korea, Private Travis King texted his US military handlers to let them know he had arrived at his gate at Incheon, the major airport serving Seoul, and was preparing to board a plane back to the US.

King, a junior enlisted soldier assigned to US Forces Korea, had faced assault charges in South Korea and was due to be removed from the US military upon his return to Fort Bliss, Texas.

But while he cleared customs and immigration, he did not get on the plane as scheduled on Monday, US officials told CNN. His escorts could not accompany him all the way to the gate to verify that he had boarded. Instead, he had booked a tour for Tuesday with a private company of the Joint Security Area inside the demilitarized zone, which divides North and South Korea.

King had checked in to an American Airlines flight bound to Dallas but reported a missing passport and didn’t board.

“He passed through all the security points up to the boarding gate but he told the airline staff that his passport was missing,” an official at the Incheon airport told CNN. The airline staff then escorted him back outside to the departure side, the official said.

On Monday, the American Airlines flight left Incheon at 6:36 p.m., according to the airline.

“He came back to the departure side of the airport at 7:02 p.m.,” the official said. American Airlines declined to comment on the incident to CNN.

When passengers have emergency situations where they cannot board a plane after passing through the immigration process, they must reverse the procedure under the immigration office’s approval.

Picture of Travis King, the US soldier who ran across the military demarcation line into North Korea on Tuesday July 18th.

While on a tour inside the demilitarized zone the next day, King inexplicably made a run for it across the demarcation line into North Korea, an eyewitness on the same tour and US officials familiar with the case told CNN. Unlike most of the heavily fortified zone, which is 160 miles long and 2.5 miles wide, the actual border line between North and South Korea inside the JSA does not have a physical barrier.

King at first tried to enter Panmungak Hall, which is a North Korean facility in the Joint Security Area, one of the US officials said. But the front door was locked – so he ran to the back of the building, at which point he was hurried into a van and driven away by North Korean guards, the official said.

“Get him!” a soldier on the South Korean side yelled, according to the eyewitness, Sarah Leslie. But it was too late.

“He was going so fast, and we were so close to the border, that he was gone by then,” Leslie added.

It wasn’t until later on Tuesday, when King failed to showed up at Fort Bliss, that the US military first realized he was missing. South Korean immigration officials also confirmed to the US that King never boarded the plane, the US official told CNN.

In this handout photo, US Private Travis T. King, seen in the bottom left wearing a black shirt and black cap, during a tour of the tightly controlled Joint Security Area (JSA) on the border between the North and South Korea, at the truce village of Panmunjom, South Korea, July 18, 2023.

Officials across the US government are now trying to piece together what might have motivated King, a US national, to willfully and without prior authorization cross into one of the most hostile countries on earth.

“I worry about him, frankly,” Army Secretary Christine Wormuth told 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.”

Warmbier was imprisoned by the North Koreans in 2016 after entering the country as part of a guided tour. North Korea released him back to the US in June 2017 but he was in a vegetative state and died shortly thereafter.

On Wednesday, the White House said it was still working to determine exactly where King is, and what his condition is.

“We are still gathering all the facts, it is still very early on,” press secretary Karine Jean-Pierre said. “The administration has and will continue to actively work to ensure his safety and the return of Private King to us and to his family,” she said.

She said the administration was working with the government of South Korea, along with Sweden, on the matter. Sweden generally represents US interests in North Korea because the US and North Korea have no diplomatic ties.

The US military has tried reaching out directly to the North Korean government to resolve the issue, officials said, but they have not yet received any response. The US believes he is still in North Korean custody but they do not have any details on his well-being or whether he is alive.

King “made a run across the demilitarized zone in the Joint Security Area, was picked up by the North Koreans, and we’ve had no contact at this point,” Adm. John Aquilino, commander of US Indo-Pacific Command, said at the Aspen Security Forum on Tuesday. “But we’re still doing our investigation to find out exactly what happened.”

Assault charges in South Korea

Just over a week before making his dash across the border, King was released from a detention facility in South Korea, where he had served 50 days doing labor, defense officials told CNN.

The punishment appears to stem from an incident in October of 2022, when King allegedly pushed and repeatedly punched a victim in the face in a club in Mapo-gu, Seoul, according to a court document from the Seoul Western District Court. He was also accused of assault in September and was consequently transferred to US military police, but those charges were ultimately dropped.

“His assault case was similar to other cases I’ve represented of young drunk men,” one of the South Korean lawyers who represented King told CNN. He said his impression of King was that he “looked like a normal guy in his early 20s.”

Before his time in the detention facility, King had been found guilty during a military court martial hearing in South Korea related to assault and other charges, a defense official told CNN. King had been demoted in rank, the official said, though it’s unclear if that came before or after the court martial.

Wormuth said Thursday that King “absolutely would have faced additional consequences” from the US Army for his conduct in South Korea, if he’d returned as planned.

“[H]e had assaulted an individual in South Korea and had been in custody of the South Korean government and was going to come back to the United States to face the consequences in the Army,” Wormuth said at the Aspen Security Forum. “And I’m sure that he was grappling with that.”

King’s mother, Claudine Gates, told ABC on Tuesday that she was “shocked” by the fact that King had crossed into North Korea.

“I can’t see Travis doing anything like that,” Gates told ABC, adding that she heard from her son several days ago, when he told her that he would be returning to his base in Fort Bliss.

At the time of his rotation in South Korea, King had no deployments on his record, and was assigned to the 6th Squadron, 1st Cavalry Regiment, 1st Brigade Combat Team, 1st Armored Division out of Fort Bliss, Texas, according to Army spokesperson Bryce Dubee.

His military awards include routine decorations provided to soldiers with his rank and experience – the National Defense Service Medal, the Korean Defense Service Medal, and the Overseas Service Ribbon.

This story has been updated with additional reporting.

CNN’s Yoonjung Seo, Oren Liebermann, Dugald McConnell and Kevin Liptak contributed reporting.