The Cheonan Incident had not only resulted in substantial changes in the security pattern of post-Cold War Northeast Asia，i.e.，from the relative ease and stability between North and South Korea to all-rounded political and military confrontation，but also in the intensification of the domineering role of the US-led US-RK and US-Japan alliances in the security issues of Northeast Asia，leading to stronger influences and containment from the US，Japan and the RK upon the Peninsula. The Incident，however，also offered the RK possibilities of new security strategies. The tense situation on the Peninsula will be controlled and the relationship between the North and South Korea is bound to blaze back to the strategic trail of co-existence and common prosperity as long as the RK could carry out a comprehensive security strategy for its north neighbor in the spirit of realizing a enduring peace and stability，denuclearization，and the ultimate goal of peaceful reunification.