2018 Moon Jae-in of the Republic of Korea on April 27 met Chairman Kim Jong Un, the president and North Korea is holding the inter-Korean summit, followed by 2018 on September 19, 2018 third in Pyeongyang.Moon Jae-in and inter-Korean summit was held at Kim Jong Un, the chairman and president the 9.19 Joint Declaration agreed. The September 19 Inter-Korean Agreement on the Military Sector is an annex to the Military Sector of the September 19 Joint Declaration. 9.19 The military agreement includes the building of military confidence in the arms control stage and the control of operational military expenditures. Those who positively evaluate military agreements and those who negatively evaluate military agreements were at odds, but they have never implemented operational military control as specifically as the September 19 military agreement in history, drawing attention from around the world. However, inter-Korean relations are at their worst, as North Korea detonated a joint liaison office just two years after the Sept. 19 military agreement. After analyzing North Korea's military actions from the September 19th military agreement to the recent bombing of the South-North Joint Liaison Office, the North Korean military action was predicted and the direction of development of arms control on the Korean Peninsula was suggested, considering the factors derived by dividing the key causes of the North's military action into internal and external causes.