After the United Nations Command and North Korea failed to reach an agreement, it is widely believed that the line was set by the UNC as a practical operational control measure a month after the armistice was signed, on August 30, 1953. However original documentation recording this has not been found. The line was originally drawn to prevent South Korean incursions into the north that threatened the armistice. However, its role has since been transformed to prevent North Korean ships heading south.