THE U.S. military identified a soldier who made an unauthorised crossing into North Korea on Tuesday as Private Travis T. King and said he was facing disciplinary action before he fled during a tour of the heavily fortified border area.

He is believed to be in custody in the North, but his exact motive and other details remain unclear.

Attempts by U.S. soldiers stationed in South Korea to desert or defect to the communist state are rare, but here are some cases that have occurred since the 1950-1953 Korean War ended with an armistice rather than a peace treaty:

- Joseph T. White shot off the lock on a gate leading into the demilitarized zone (DMZ) separating the Koreas while a U.S. soldier stationed in South Korea in 1982, before surrendering to North Korean troops, according to an account published by the Korea Times.

The North claimed he had defected, though Pyongyang refused a request by the United Nations Command to meet him. A U.S. military spokesman later said an investigation indicated that White crossed into North Korea of his own free will. In a video released by the North, White denounced the United States and praised North Korea and its then leader Kim Il-Sung.

White's parents later received a handwritten letter believed to be from their son, in which he said he was working as a teacher and happy in the North, the Washington Post reported. White drowned in a swimming accident in the North in 1985, according to a media report, citing information received by his parents.

- Charles Robert Jenkins walked into North Korea when on patrol on the DMZ in 1965. He later expressed regret for fleeing and explained at his court marital that his motive was to avoid hazardous duty in South Korea and combat in Vietnam. Jenkins said he had drunk 10 beers before the incident.

During his near four decades in the North, he taught English and also portrayed a U.S. spy in a propaganda film. Jenkins married Hitomi Soga, a Japanese woman abducted by Pyongyang. Soga was allowed to return to Japan in 2002 and Jenkins joined her with their two daughters in 2004. Jenkins died in 2017.

- James Joseph Dresnok was a 21-year old U.S. army private stationed in South Korea in 1962 when he fled to the North. Facing a court martial for skipping duty, Dresnok describes in a film about his life how he bolted across the DMZ, through a minefield. Dresnok and three fellow American military defectors including Jenkins, Jerry Wayne Parrish and Larry Allen Abshier lived in relative isolation for years before becoming stars of North Korean cinema by depicting evil Americans in propaganda movies promoted by then leader Kim Jong-Il. Reports, citing Dresnok's sons, say he died in Pyongyang in 2016.