Unification is the last revolutionary task of Korea in that the division of country has became obstacles that have been placed in our path. Inter-Korean relation is an existent struggle that has three aspects; intention, purpose, potential ability. All these three aspects are geared towards warfare and subversion. The only reason for existence of North Korea is to bring about a revolution in South Korea. The North is a regime that constantly pursues the revolution to concentrate and control North Koreans. Since the North and the South wage an existent struggle over value, North Korea should be treated with power that fulfills certain value. In light of unification based on above premises, the four stages are prerequisite for two governments to unify; agreements of ideology (value), how to build politics and society based on united ideology, political and economical unification and military consolidation. The ideology issue has not been agreed between the South and the North. In the South-North talks, North Korea has pushed forward the Korean race as in ideology but a slogan "by ourselves" is nothing but a strategy by the North. I would like to modify and complement three community policies proposed by President Lee. The peace community is not effective because any agreement can be politically taken advantage of by each side. The ground of economic community is very vulnerable. North Korea will collapse once it adopts an open-door policy and reformation that are prerequisite for the North to survive. A policy of an ethnic community should not be sentimentally approached because 2 different peoples without any homogeneity exist in North and South Korea. The only way we can pursue unification is through the collapse of the North Korea. To strengthen solidarity of people in South Korea is the most important to achieve the goal. Coercive diplomacy should be considered without the exclusion of preemptive attack. Solidarity of people, coercive and offensive diplomacy are the core of liberal democratic realism.