By Idrees Ali and Phil Stewart

WASHINGTON (Reuters) -North Korea has offered a very brief response to the United Nations Command about a U.S. soldier who dashed over the heavily-guarded border with South Korea on July 18 and was immediately taken into custody, the Pentagon said on Tuesday.

However, Pentagon spokesperson Brigadier General Patrick Ryder said that North Korea only acknowledged the U.N. Command's request for information about U.S. Army Private Travis King and stopped short of offering detailed information about him.

"I can confirm that the DPRK has responded to United Nations Command, but I don't have any substantial progress to read out," Ryder told a press conference, using the acronym of North Korea's official name, the Democratic People's Republic of Korea. When pressed, Ryder said that North Korea's message back to the U.N. Command was just "an acknowledgement" of the U.N. Command's inquiry.

King sprinted into North Korea on July 18 while on a tour of the Demilitarized Zone on the border, landing the United States in a new diplomatic quandary with nuclear-armed North Korea.

King, who joined the U.S. Army in January 2021, had served as a Cavalry Scout with the Korean Rotational Force, part of the decades-old U.S. security commitment to South Korea.

But his posting was dogged by legal troubles.

He faced two allegations of assault in South Korea, and eventually pleaded guilty to one instance of assault and destroying public property for damaging a police car during a profanity-laced tirade against Koreans, according to court documents.

From May 24 to July 10 he served a sentence of hard labor at the Cheonan correctional facility in lieu of paying a fine, Yonhap news agency reported.

After his release from the prison, which is designated for U.S. military members and other foreigners, King stayed at a U.S. base in South Korea for a week, Yonhap said.

A Cheonan prison official confirmed King had served the hard labor sentence there, but declined to provide further information citing privacy concerns.

U.S. officials, who spoke on condition of anonymity, said King had been due to face military disciplinary action on his return home to Fort Bliss, Texas.

U.S. officials have expressed deep concern over King's fate in North Korea. The Army has noted the case of Otto Warmbier, a U.S. college student who was imprisoned in North Korea for 17 months and died shortly after he was returned to the United States in a coma in 2017.

(Reporting by Idrees Ali and Phil Stewart; Editing by Grant McCool)