An unidentified United States national defected to North Korea from the South Korean side of the Joint Security Area while in the heavily fortified demilitarized zone on Tuesday, the United Nations Command confirmed.

The Korea Herald learned that the defector was a US soldier, although it was unable to confirm if he was stationed in South Korea or had been visiting the country as a tourist.

"A US National on a JSA orientation tour crossed, without authorization, the Military Demarcation Line into the Democratic People’s Republic of Korea (DPRK)," the UN Command said in a statement, referring to North Korea by its official name.

The JSA is an area in the DMZ that spans the military demarcation line, which serves as the dividing line between South and North Korea.

"We believe he is currently in DPRK custody and are working with our KPA counterparts to resolve this incident," the UN Command added.

KPA stands for the Korean People's Army, which is the North Korean military.

South Korea's Joint Chiefs of Staff referred the incident to the UN Command, declining to provide any comment on the matter.