This article is to explore Kim Jeong-un regime`s charater and the changes of military strategy by economic difficulties. North Korea has attacked Yeonpyeong island and the Cheonan warship in 2010. The two attacks were not discrete but overlap and interweave under a definite purpose. It was a provocation to gain a strong trust between new heir of North Korea and ‘North Korean sympathizers’ in South Korea. So, Kim Jeong-un`s regime could be called the provocative and offensive. Since the mid-1990s, North Korea`s economic hardship has brought the decline of the combat strength the hardship of war preparation and the unbalanced development of military power. Furthermore, South Korean military`s defense capability has been increasing and the weakness of North Korean military strategy has been larger. The change of military strategy in Kim Jeong-un`s regime was inevitable. It tuned into the military strategy could strike the targeted area and object faster and deadlier than in the past. The forms are “all-out war”, “asymmetric local war” and “local war linked Pro-North Koreans”.