North Korea had 6th Nuclear Test and Hwasung-15 ICBM launching, then declared 'Nuclear Weapon Accomplishment'. And there were words of 2th Korean War, 3th World War and Nuclear War. But in 2018, there were three time South-North summit talks and one time U.S.-N.K. Summit Talks with PyeongChang Winter Olympic Games. And then Korean Peninsula was started to be made to peace mode. At the same we expected N.K. denuclearization and pease regime of Korean Peninsula. On the other hand, war is not a devil but a phenomenon of international society, so we must understand and manage a nature of war. So, Korean Forces always have to prepare war in peace atmosphere. First, this paper made a framework for analysis formed by 3 Images of Kenneth Waltz and 3 Viewpoints of Joseph Nye, Jr. That is are international system, national system and political leader individual personality as 3 viewpoints. Next, this paper analyzed the Origins of war of the Sino-Japanese War and 1th World War. And this paper analyzed Sion-Japanese and 1th World War comparatively, so studied a Implication and a suggestion in East Asia-Pacific Region and Korean Peninsular. In conclusion, Korean society oriented pease, at least military have to provide against War. That is a responsibility and a duty of military.