A demilitarized zone (DMZ) is an area in which treaties or agreements between states, military powers, or contending groups forbid military installations, activities, or personnel. It is an area agreed upon between the parties to an armed conflict, which cannot be occupied or used for military purposes by any party to the conflict. A DMZ often lies along an established frontier or boundary between two or more military powers or alliances. It may sometimes form a de facto international border, such as the Korean Demilitarized Zone. The DMZ is a 148-mile-long strip that incorporates territory from both North and South Korea. It is about 35 miles from South Koreas capital, Seoul, and runs along the 38th parallel, the line that divides the two countries, along which much of the Korean War occurred. The DMZ ensures the demarcation between North and South Korea remains peaceful and is protected by heavily armed troops on both sides.