Preemptive Strategy, namely preventative self-defense right called by Americans, brings enormous impact and influence on international ruling of law especially the United Nations Charter and collective security system based on the charter, which puts the United Nations in danger of marginalization for a time.

On Collective Security System from the Angle of the Iraqi War;

The American government,out of hegemonism and power politics,launched the Iraq Wars on the excuse of "preemptive strike" as a self-defense right and brought instability to international community,which constitutes a great threat to the UN collective security system.

The new world order designed by him is the collective security led by the United States, which is different in nature from that of Wilson.

It has,at least,the following impacts: compensating,to a certain extent,for the inadequate UN collective security mechanism,enhancing the UN efficacy in maintaining peace and security,creating an UN "peacekeeping operation" mechanism,launching an UN emergency session which is helpful to the containment of hegemony and the realization of democratization in internat.

North Korea Nuclear Crisis and the Consideration of Building up North-east Asian Security System;