The United Nations is in talks with North Korea over the US soldier who fled across the heavily militarized border and into the undercover state last week, a senior UN official said Monday.

Private Second Class Travis King, 23, was about to fly back to the United States from South Korea for possible disciplinary action after refusing to pay a fine for allegedly damaging public property.

He escaped from his military escort at the airport last week and managed to join a guided tour of the Joint Security Area, a UN-administered North-South ground.

Although the North Koreans did not say publicly about King, the UN force handling inter-Korean negotiations said it was in talks with the North about the fugitive soldier.

«The main concern for us is the well-being of Private King,» said Lt. Gen. Andrew Harrison, a British army officer who serves as deputy commander of the United Nations Command, known as UNC.

Speaking at a news conference in Seoul, Harrison said the dialogue was taking place through a mechanism established after the North-South armistice, which was signed in 1953 to stop fighting in the Korean War.

«I can’t say anything that would hurt that process,» Harrison said. «Much of this remains unknown.»

Asked by NBC News if King was being treated as a deserter, Harrison said, «We haven’t characterized Private King as anything other than an American soldier at this point.»

Last week, Defense Department spokeswoman Sabrina Singh said the United States had not received a response when it inquired about King’s whereabouts and well-being. The United States does not have embassy-level relations with North Korea, but sent the message through Swedish officials, its usual solution.

The incident provides another flashpoint between the West and North Korea, a repressive nuclear-armed state that shares a complicated alliance and trading relationship with China.

North Korea says it fears Western-backed regime change and has repeatedly threatened to launch a nuclear attack to prevent it. The United States and its allies say the world cannot live with this threat and have vowed to denuclearize the Korean peninsula.

On Saturday, the North fired several rounds of cruise missiles into the Yellow Sea, an apparent protest against the deployment of a US nuclear-armed submarine in South Korea.

In an April meeting between President Joe Biden and South Korean President Yoon Suk Yeol, Biden warned that «a nuclear attack by North Korea against the United States or its allies and partners is unacceptable and will result in the end of any regime that takes such action.»

matt bradley contributed.