North Korea invaded the South on June 25, 1950, invading most of the country. In September 1950, the United Nations force, led by the United States, intervened to defend the South and headed for North Korea. As the border with China approached, Chinese troops intervened on behalf of North Korea and shifted the balance of war. The fighting ended on July 27, 1953 with a ceasefire that almost restored the original borders between North and South Korea.  Syngman Rhee refused to sign the ceasefire, but reluctantly agreed to abide by it.  The ceasefire opened an official ceasefire, but did not result in a peace treaty. It built the Korean Demilitarization Zone (DMZ), a buffer zone between the two sides, which cut the 38th parallel but did not follow it.  North Korea announced that it would not abide by the ceasefire at least six times in 1994, 1996, 2003, 2006, 2009 and 2013.   In December 1991, the two States reached an agreement on reconciliation, non-aggression, trade and cooperation, in which non-aggressive and cultural and economic exchanges were concluded. They also agreed on a prior report of major military movements and created a military assistance line and worked to replace the ceasefire with a “peace regime”.
  On 31 August, it was reported that South Korean President Moon Jae-In would send a special delegation to North Korea on 5 September to continue the nuclear talks and set the date for the summit.   On September 5, 2018, South Korean National Security Adviser Chung Eui-yong, Director of National Secret Service Suh Hoon and other delegates traveled to North Korea to arrange a meeting with Kim Jong-un, where they organized the summit and helped to save the weakening of nuclear diplomacy between the United States and North Korea.  It was then announced that the three-day summit would take place between 18 September and 20 September.  South Korean government officials have insisted that Kim Jong-un set a proposed denuclearization schedule and work with Trump to achieve this goal.  Shortly after the signing of the agreement, the South Korean military gave press briefings to clarify three points. First, South Korea will work closely with the international community to ensure compliance with U.N. economic sanctions against North Korea. Second, the agreement does not limit any defensive action that the South may have to take to counter aggressive military action by the North.