An American soldier who crossed into North Korea without authorization on Tuesday has been taken into custody by North Korean authorities, according to U.S. officials.
The service member crossed into North Korea during a tour of Panmunjom, or the Joint Security Area, which straddles the inter-Korean border, becoming the latest U.S. citizen to be detained by the isolated Communist country.
The soldier had recently been released from a South Korean prison after being arrested on assault charges, according to a U.S. official familiar with the situation who was not authorized to speak on the record. He was to return to Fort Bliss, Texas, to face additional military disciplinary actions.
The service member was escorted to the airport, but instead of boarding his plane, he joined a tour of the Joint Security Area, where he broke away from the group and ran across the border, the official said. The tour guides chased after him, but did not catch him, and he was seen being taken into custody by North Korean soldiers.
The soldier, whose identity has not been released, “willfully and without authorization crossed the Military Demarcation Line into the Democratic People’s Republic of Korea,” said Col. Isaac Taylor, a public affairs officer for the U.S. Forces Korea.
“We believe he is currently in D.P.R.K. custody,” Colonel Taylor said, adding that U.S. officials were working with their counterparts in the North Korean military to resolve the incident.
The United States and North Korea have no formal diplomatic relations, and U.S. interests in the country are formally represented by the Swedish Embassy there.
During a news conference on Tuesday, Defense Secretary Lloyd J. Austin III said the U.S. military was “closely monitoring and investigating the situation, and working to notify the soldier’s next of kin.”
“I’m absolutely foremost concerned about the welfare of our troop,” Mr. Austin said.
The American-led United Nations Command first confirmed the border crossing Tuesday.
Both the U.N. Command and the North Korean People’s Army keep duty officers at Panmunjom, the sole point of contact on the 155-mile-long Demilitarized Zone that separates the two Koreas.
The U.N. Command allows tour groups in the Joint Security Area, which was created as part of the 1953 armistice that halted the Korean War 70 years ago next week. Tourists can visit the area from South Korea while unarmed soldiers trail closely behind.
The soldier detained on Tuesday was the first known American held in North Korean custody since Bruce Byron Lowrance was detained for a month after illegally entering the country from China in 2018.
The American student Otto F. Warmbier was arrested in Pyongyang in 2016, accused of trying to steal a propaganda poster from the wall of his hotel. Mr. Warmbier was sentenced to 15 years in prison. After being held for 17 months in North Korea, Mr. Warmbier, then 20, was flown from Pyongyang to Ohio, his home state, in a coma in June 2017. He died a week later.
Although the inter-Korean border is strewn with land mines and guarded by layers of tall barbed-wire fences, people from both Koreas have crossed the DMZ, as have several American soldiers stationed in the South.
In 2014, an unidentified American was detained on a riverbank near the South’s western border with North Korea after trying to swim into the North. After he was apprehended, he told South Korean officials that he had intended to go to North Korea to meet its leader, Kim Jong-un. Before he entered North Korea from China, Mr. Lowrance was also detained by South Korean soldiers while approaching the inter-Korean border.
But defections through Panmunjom are highly unusual.
A South Korean soldier assigned to the Joint Security Area defected to the North in 1991. In 2017, a North Korean soldier ran across Panmunjom through a hail of bullets from fellow Communist soldiers trying to stop him. The defector survived multiple bullet wounds.
Relations between North Korea and the United States have deteriorated in recent years as the North has ramped up its nuclear and missile programs, defying international sanctions.
The fate of American citizens held in North Korea is not always clear. Some are voluntarily released, while others have faced criminal charges of committing “hostile acts” and have been freed only when American officials, like former President Bill Clinton, have visited Pyongyang to request their release.
North Korea released three American detainees in 2018 after Secretary of State Mike Pompeo visited Pyongyang to pick them up. North Korea treated their release as a sign of good will and a merciful diplomatic gesture aimed at facilitating Mr. Kim’s summit meeting with President Donald J. Trump in Singapore later that year.
Panmunjom has long been a popular tourist destination for foreign visitors in South Korea. It is the only place inside the 2.5-mile-wide DMZ where tourists are allowed. It is also the only place where outsiders can sometimes watch North Korean soldiers at close hand.
On a typical tour, visitors are escorted into the Joint Security Area by South Korean and U.S. soldiers wearing U.N. arm bands. They look at the Bridge of No Return, where Korean prisoner of war exchanges took place in 1953. They also visit a monument to a South Korean soldier who was shot dead during a gunfight triggered by a Soviet citizen’s defection to the West through Panmunjom in 1984.
At Panmunjom, no wall or fence separates the two Koreas. Only a low-rising cement slab barely a half-foot tall marks the official demarcation line. But no visitors from either side are allowed to step over the line, as President Trump did when he met Mr. Kim in 2019. A highlight of the tour comes when visitors are escorted into a blue joint conference room and are allowed to walk into the North Korean half.
North Korean soldiers watch the visitors from the South carefully, sometimes staring into the joint conference room. But since the pandemic, they have avoided coming closer to outside visitors.
Choe Sang-Hun reported from Seoul, Michael D. Shear and John Ismay from Washington. Edward Wong contributed reporting from Washington.