The U.S. withdrew the troops from South Vietnam and the ROK on the basis of the Nixon Doctrine, implemented détente that supported relaxing international tension by U.S.-China reconciliation, and pursued peaceful coexistence on the premise of the status quo in Asia. This is the reason why I focus on the Vietnam War which had been the background that caused structural changes of the Cold War in East Asia. And, the Vietnam War was the first test case that the U.S. and South Korea cooperated in the actual combat since the formation of the alliance. The experience in Vietnam was the opportunity for the ROK government to know the possibility and the degree of the support from the U. S. in times of emergency.

However, few previous studies have ever been done on the Vietnam War from South Korean viewpoints of the U.S.-ROK alliance. In that sense, the questions caused by the foreign policy of the U.S. must be demonstrated as follows; first, as a divided country like South Vietnam, what did the ROK government think about the U.S. support in combat? Secondly, while peace negotiations went on, what was considered necessary by the South Koreans? Thirdly, after Paris Peace Accords, what were South Korean views on it and how did the ROK government respond to the problem by its policy? Lastly, how did Koreans feel about the fall of Saigon and what was the difference between the U.S. and South Korea on the Korean Peninsula issues of post-Vietnam War?

The purpose of this paper is to explore further into the Vietnam War, associated with the ROK and the U.S.-ROK alliance, based on the diplomatic archives. Especially, I would like to focus attention on the question of how the ROK government dealt with Vietnam’s situation in the process of US withdrawal and what happened to its way between self-defense and the alliance since then.

Through the whole analysis, the following conclusions were obtained; the first is South Korea became aware of partnership from the patron-client relationship and the transferring of operational control of South Korean forces because of the Vietnam War. The second is unilateral US withdrawal plan and the end of the war by negotiations decreased reliability of US military commitment in ROK. Nevertheless, South Korea also reconfirmed that the alliance was indispensable to the national security. The third is the U. S. reduced the possibility of direct intervention in conflict on the Korean peninsula after the Vietnam War. One final point is the Vietnam War was a factor to accelerate self-defense policy in Seoul.