Travis King: US says North Korea 'has not answered' calls to negotiate soldier's release
United States officials have said North Korea is not responding to attempts to discuss the release of an American solider who crossed its heavily armed border.
Private Travis King ran into North Korea while on a civilian tour of the border village of Panmunjom, on Tuesday.
The 23-year-old is the first known American to be held in North Korea for nearly five years.
A spokesperson for the US State Department told reporters on Wednesday: "Yesterday, the Pentagon reached out to counterparts in the [North] Korean People's Army.
"My understanding is that those communications have not yet been answered."
The US and North Korea fought during the 1950-53 Korean War and are still technically at war since that conflict ended in a truce, not a peace treaty. The states have no diplomatic ties.
In the past, the Swedish Embassy, in Pyongyang, has acted as a liaison for the US.
The US can also reach North Korea via a hotline at the American-led United Nations (UN) Command in Panmunjom - known as the "pink phone".
King's motives for crossing into North Korea are not known, although he was due to be escorted to an airport in South Korea that same day for a flight back to the United States.
He had been released from a South Korean prison on July 10 after serving time for assault, and was scheduled to return to Fort Bliss, Texas.
At the airport, King's escorts could not get past a security checkpoint with him, creating an opportunity for him to leave the airport.
New Zealander Sarah Leslie, who was part of the same tour group as Travis King, describes the moment she witnessed him sprint into North Korea
He then joined a group of 43 tourists in South Korea, who were visiting the Demilitarised Zone, which separates South and North Korea.
Towards the end of the tour, as it took in the border village of Panmunjom, King ran into North Korea.
Meanwhile, North Korea's defence minister, Kang Sun Nam, issued a statement, which called a recent US submarine deployment "the most undisguised and direct nuclear threat" to North Korea.
He warned the deployment may be one of the situations foreseen in a new law, which authorised the preemptive use of nuclear weapons in a broad range of cases.
Some experts have speculated that North Korea will not easily release King given his status as a US soldier and citizen.
But previous American civilian detainees have been released after the United States sent high-profile missions to Pyongyang to secure their freedom.
Bruce Byron Lowrance was the last American known to be held by North Korea, who, according to North Korean state-run media, crossed from China into the country.
He was released back to the United States in 2018.
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