Along the Korean peninsula is the one hundred and fifty-five mile long demilitarized zone (DMZ) dividing the North and South. It is four kilometers wide and divided by the Military Demarcation Line (MDL). The northern edge of the DMZ is called the Northern boundary and the Southern edge is called the Southern boundary.

Along the Southern boundary, the Republic of Korea (ROK) armed forces have established General Out Posts (GOP) and, within the space between the MDL and southern boundary, guard posts (GP).