North Korea has confirmed custody of Travis King in its first response to requests for information on the US soldier's whereabouts, the UN Command has said.
The 23-year-old private dashed across the border from South Korea on 18 July while on a guided tour.
The UN Command said it would not give more details about Pyongyang's response at this time.
It said it "did not want to interfere with the efforts to bring him home".
However, the reply indicates Pyongyang could be ready to start negotiating.
The UN Command, which polices the Demilitarised Zone (DMZ), had sought information on Private 2nd Class (PV2) King using its direct phone line to the North Korean Army [KPA] in the Joint Security Area.
"KPA has responded to the United Nations Command with regards to PV2 King. In order not to interfere with our efforts to get him home, we will not go into details at this time," a statement said.
The North Koreans had previously acknowledged the request but this is the first time they have responded, confirming the US solider is in their custody.
North Korea has not publicly acknowledged custody of PV2 King.
Before he crossed the border, PV2 King served two months in detention in South Korea for assault charges. He was released on 10 July.
He was supposed to fly back to the US to face disciplinary proceedings but managed to leave the airport and join the DMZ tour.
He is a reconnaissance specialist who had been in the army since January 2021 and was in South Korea as part of his rotation.
The Demilitarised Zone (DMZ) separates the two Koreas and is one of the most heavily fortified areas in the world.
It is filled with landmines, surrounded by electric and barbed wire fencing and surveillance cameras. Armed guards are supposed to be on alert 24 hours a day.
The DMZ has separated the two countries since the Korean War in the 1950s, in which the US backed the South.
The war ended with an armistice, meaning that the two sides are still technically at war. Tens of thousands of US troops remain in the South.
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Watch: What's next for captured US soldier in North Korea
As the US and North Korea do not have diplomatic relations, the Swedish embassy in Pyongyang tends to negotiate on behalf of the US. Currently its diplomatic staff are not in the country, because of the ongoing border closure since the pandemic.
Both the UN Command, that runs the border area, and the South Korean military have direct phone lines to the North Korean military, that they call daily to check in, though the North Koreans do not always pick up.
In recent years, a number of American citizens who illegally entered North Korea – excluding those convicted of criminal activity there – have been released within six months.
The detention of the soldier presents a major foreign policy headache for US President Joe Biden. PV2 King is believed to be the only American citizen currently in North Korean custody. Six South Koreans remain in detention there.
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