The United States on Thursday voiced mounting concern over Army Private Travis King, who dashed into North Korea two days ago, saying Pyongyang had a history of mistreating captured Americans.
U.S. Army Secretary Christine Wormuth, in her first public comments on the case, said Washington was fully mobilized in trying to contact Pyongyang, including through United Nations communications channels.
But North Korea had yet to offer any response, officials said.
"I worry about him, frankly," Wormuth told the Aspen Security Forum in Colorado. She cited the case of Otto Warmbier, a U.S. college student who was imprisoned in North Korea for 17 months before dying shortly after he was returned to the United States in a coma in 2017.
"I worry about how they may treat him. So, (we) want to get him back."
At the White House, National Security Council spokesperson John Kirby also expressed concern: "This is not a country that is known for humane treatment of Americans - or frankly anybody else for that matter."
American officials remained stumped about why King ran across the border into North Korea. But Wormuth acknowledged he was likely worried about facing further disciplinary action from the Army upon his return home to the United States.
She said she was not aware of any information demonstrating the 23-year-old was a North Korea sympathizer, and the Pentagon played down suggestions he might present an intelligence liability.
Pentagon spokesperson Sabrina Singh said the U.S. Army's counter-intelligence office and U.S. forces in South Korea were carrying out an investigation into what drove King to make such a puzzling decision.
King was on a civilian tour of the Panmunjom truce village on Tuesday when he dashed across the Military Demarcation Line that has separated the two Koreas since the Korean War ended with an armistice in 1953.
King had been fined for assault while stationed in South Korea and had been detained for more than a month before being escorted to Incheon International Airport by the U.S. military for a commercial flight to Dallas, Texas, according to U.S. officials.
Once past security checks, he told airline staff at the departure gate he had lost his passport and returned to the terminal, an airport official told Reuters on condition of anonymity.
Wormuth said King "may not have been thinking clearly, frankly."
"He 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 and face the consequences in the Army," she said. "I'm sure that he was grappling with that."