A U.S. soldier was believed to have been detained by North Korea on Tuesday after crossing into the country while on a tour of the heavily fortified Joint Security Area at the border with the South.

"A U.S. National on a JSA orientation tour crossed, without authorization, the Military Demarcation Line into the Democratic People’s Republic of Korea," the United Nations Command said in a statement. "We believe he is currently in DPRK custody and are working with our KPA counterparts to resolve this incident."

KPA refers to the North's Korean People's Army.