The person moved into the North during a tour to the Joint Security Area in the Demilitarized Zone (DMZ) and is believed to be in North Korea's custody, according to the UNC, Yonhap news agency reported.
The command did not elaborate on the person's gender or other details, according to the report
"We ... are working with our KPA counterparts to resolve this incident," the UNC said in a tweet referring to the North Korean People's Army.
The UNC oversees activities in the DMZ.
MNA/PR