The Neutral Nations Supervisory Commission (NNSC) was established by the Korean Armistice Agreement signed 27 July 1953, declaring an armistice in the Korean War. It is, with the Military Armistice Commission, part of the mechanism regulating the relations between the Democratic People's Republic of Korea (DPRK, North Korea) and the Republic of Korea (ROK, South Korea).

The mission of the NNSC was to carry out inspections and investigations to ensure implementation of sub-paragraphs 13(c) and 13(d) of the Armistice, which were to prevent reinforcements being brought into Korea, either additional military personnel or new weapons, other than the piece-for-piece replacement of damaged or worn out equipment. Reports were to be made to the Military Armistice Commission.

According to the Armistice, the NNSC shall be composed of four senior officers, two of whom shall be appointed by neutral nations nominated by the United Nations Command (UNC) and two of whom shall be appointed by neutral nations nominated jointly by the Korean People's Army (KPA) and the Chinese People's Volunteers (CPV). The term "neutral nations" was defined as those nations whose combat forces did not participate in the hostilities in Korea. The United Nations Command chose Switzerland and Sweden, while the Korean People's Army and Chinese People's Volunteers chose Czechoslovakia and Poland.

The NNSC was supported by twenty Neutral Nations Inspection Teams, ten permanently located at ports in North and South Korea, and ten mobile teams. The Armistice did not specify the manner of operation of the teams. The Swiss and Swedish teams were of a small size, relying on their hosts to provide personnel support, vehicles, and communication equipment to report back to the Supervisory Commission. The Czechoslovak and Polish teams were much larger and fully self-sufficient, including heavy radio trucks, interpreters, cooks and mess equipment.