With the signing of the Paris Peace Accord in 1973, President Nixon brought the direct involvement of the United States in the Vietnam War to an end. The Paris Agreement has been widely recognized as one of the most successful results of Nixon and Kissinger's “realist” diplomacy. However, in light of the recent opening of masses of archival materials, a reassessment of “Nixinger” diplomacy has been taking place.<br>Regarding the endgame of the Vietnam War, there has been controversy about whether the Paris Agreement represented the principles of “peace with honor” or “decent interval”. On the one hand, some scholars argue that the US persisted with the concept of “peace with honor”. In other words, the US sought peace that would guarantee lasting non-communist South Vietnamese independence. On the other hand, other scholars argue that the US simply pursued the strategy of placing a “decent interval” of time between US withdrawal and the collapse of South Vietnam. Namely, they insisted that the US admit to the 1975 collapse of South Vietnam in advance. Because of the actual collapse of the Saigon government in 1975, the “decent interval” theory is becoming the standard explanation.<br>The “decent interval” theory is based on a tacit assumption. The premise is that due to the successful result of Sino-US-Soviet triangular diplomacy, the US perceived a decline in the importance of the Vietnam War and her “credibility” as a superpower no longer depended on the fate of the South Vietnam. Indeed, the US succeeded in creating the strategic environment in which both the Chinese and the Soviets sought improvement of their relationships with the US. Accordingly, Kissinger suggested to Nixon that the “decent interval” solution could be a reasonable way to end the war.<br>However, Sino-US-Soviet triangular diplomacy actually brought about increased military assistance from the USSR and China to North Vietnam. Furthermore, Hanoi started the “Spring Offensive” in 1972 to destroy South Vietnam. As an unintended result, Indochina became an area of intensified Sino-Soviet competition and Hanoi stiffened its intransigence. Contrary to the Nixon Administration's expectations, the VietnamWar did not become localized. In this situation, Nixon could not give up the pursuit of “peace with honor”, as a North Vietnamese victory supported by the USSR and China meant the loss of US “credibility” as a superpower.<br>In this article, I argue that although President Nixon understood the possibility of the collapse of South Vietnam after a “decent interval” from US withdrawal, he could not abandon the search for “peace with honor” in order to avoid the loss of US “credibility”.