Talks between the UN Command and North Korea over an American soldier who ran into the North from South Korea are underway, the group’s deputy commander said.

Andrew Harrison, a British lieutenant general, refused to say when the conversation started, how many exchanges have taken place and whether the North Koreans have responded constructively, citing the sensitivity of the discussions.

He also declined to detail what the command knows about Private Travis King’s condition.

“None of us know where this is going to end,” Lt Gen Harrison said during a press conference in Seoul on Monday.

“I am in life an optimist and I remain optimistic. But, again, I will leave it at that.”

It was not immediately clear if Lt Gen Harrison’s comments referred to meaningful progress in communications after the command said in a statement last week it was “working with” its North Korean counterparts.

The UN Command, created to fight the Korean War, has remained in South Korea to supervise the implementation of the 1953 armistice that stopped the fighting in the conflict.

The contact happened through “mechanisms” set up under the armistice, Lt Gen Harrison said.

That could refer to the so-called pink phone, a telephone line between the command and the North Korean army at the border truce village of Panmunjom, where Mr King crossed.

The Koreas are still technically at war since a peace treaty was never signed.

The US, which fought alongside the South Koreans and other allies during the war, never established diplomatic relations with the North but the line is a common way they communicate.

North Korea has remained publicly silent about Mr King, who crossed the border during a tour of Panmunjom while he was supposed to be heading to Fort Bliss in Texas after his release from prison in South Korea on an assault conviction.

US officials have expressed concern about his wellbeing and said previously North Korea ignored requests for information about him.

Analysts say North Korea may wait weeks or even months to provide meaningful information about Mr King to maximise leverage and add urgency to US efforts to secure his release.

Some say North Korea may try to wrest concessions from Washington, such as tying his release to the United States cutting back its military activities with South Korea.

Mr King’s crossing came at a time of high tensions in the Korean Peninsula, where the pace of both North Korea’s weapons demonstrations and the United States’ combined military exercises have intensified in a tit-for-tat cycle.

On Monday, South Korea’s military said a nuclear-propelled US submarine arrived at a port on Jeju Island.

The arrival of the USS Annapolis adds to the allies’ show of force to counter North Korean nuclear threats.

Last week, the USS Kentucky became the first US nuclear-armed submarine to arrive in South Korea since the 1980s.

North Korea reacted to its arrival by test-firing ballistic and cruise missiles in apparent demonstrations that it could make nuclear strikes against South Korea and deployed US naval vessels.

North Korea’s defence minister also issued a veiled threat, saying the Kentucky’s docking in South Korea could be grounds for the North to use a nuclear weapon against it.

North Korea has used similar rhetoric before but the statement underscored how strained relations are now.

The US and South Korea have expanded their combined military exercises and increased regional deployments of American aircraft and ships, including bombers, aircraft carriers and submarines in a show of force against North Korea, which has test-fired around 100 missiles since the start of 2022.

The Annapolis, whose main mission is destroying enemy ships and submarines, is powered by a nuclear reactor but armed with conventional weapons.

The Annapolis mainly docked at Jeju to load supplies but Jang Do Young, a spokesperson of South Korea’s navy, said the US and South Korean militaries were discussing whether to arrange training involving the vessel.