The article focuses on the analysis of US-Vietnam relations during the period from 1945 to 1975. The aim of the article is to trace the changes that took place in the US-Vietnam relationship over that period, to identify the factors that influenced them, as well as the approaches used by the heads of the countries to tackle their foreign policy objectives in the region. The author traces the evolution of US policy in Vietnam pursued by Presidents H. Truman, D. Eisenhower, J. Kennedy, L. Johnson and R. Nixon. The United States had diametrically opposed position on relations with the Vietnamese governments, namely, confrontation and military conflict with the Democratic Republic of Vietnam, and cooperation, military and economic aid to the Republic of Vietnam. The author concludes that the US attitude towards Vietnam was determined by the international situation at that time, including the beginning of the Cold War. The policies of Presidents D. Eisenhower and J. Kennedy were to restrain the expansion of the Communist bloc's sphere of influence. The direct involvement of the US military in the Vietnam conflict, initiated by L. Johnson, pursued the goal of enhancing the prestige of the United States in the global confrontation with the USSR. The split between the Soviet Union and China was used by the US to get out of the Vietnam War and mend relations with China as a counterweight to the Soviet Union in the Asia-Pacific region. Instead, the Republic of Vietnam, which had been the "junior partner" of the United States, was left to its fate.