The impact of the Truman Doctrine on Vietnam
Beginning in the 1950s, maintaining a non-communist South Vietnam became crucial in American efforts to contain communism. There were America’s justification for its actions in South Vietnam in the 1950s and its determination to abide by the outcome of free elections there only if those elections yielded a non-communist leader.
The reason that made the U.S enter into the scene during the Vietnam war was based on what the then U.S. President Dwight D. Eisenhower referred to as the domino effect. In his April 1954 speech that addressed communism in the then Indochina, he argued that when one thought about the communism deeply, it brought the idea of what one would term as the “falling domino” principle; whereby in a dominoes setting, knocking the first one leads to the eventual fall of the last one.
In the America’s reasoning, the fall of Southeast Asia to Communism would eventually lead to the fall of those adjacent countries. With the French colonials in the non-communist South Vietnam and North Vietnam being communist supported by China and the Soviet Union; the U.S thought it crucial to assist France with aid in defeating the North invasion that was lead by the revolutionist Ho Chi Minh. U.S being a democratic nation, it feared that communism shunned democracy, didn’t respect human rights and it didn’t trade with capitalist nations because of its closed state economies polices. Therefore, in the eyes of the American pro-war leaders the Vietminh, the North Vietnam government, Ho Chi Minh and the National Liberation Front were agents of global communism; and were fitful for destruction so as to avoid Veitnam, albeit based in their “domino theory”, becoming the subsequent Asian domino.
The U.S had the determination to abide by the free outcomes in the 1956 Vietnam elections if only those elections yielded a non-communist leader (Bostdorff, 2008). According to the Geneva Accords, there would be general elections in Vietnam in the year 1956 so that South Vietnam and North Vietnam could be unified. However, America was against the Accords because it was not certain if the unified nation could not fall to the communism rule. Basing their argument on the Geneva Accords’ political protocols, the U.S. Secretary of State under President Eisenhower’s administration, John Foster Dulles opined that the Vietnamese communists had been accorded more power. To support Dulles’ opinion, President Eisenhower just like other senior American experts propped his views by claiming in 1954 that comparing the election of the non-communist Emperor Bao Dai and the communist Ho Chi Minh, it was “possible 80% of the population would have voted for the communist Ho Chi Minh as their leader.” President Eisenhower filed the question in, “how can we expect ‘free elections’ to be held in the Communist North?”
Thus, the America’s justification for its determination to abide by the outcome of free elections in Vietnam only if those elections yielded a non-communist leader were based on its fears that by the election, [it feared that] the communists could have won it. Thus after winning, the communism administration could introduce communist policies that America feared. Also, conformed well with their campaign to prevent global communist agents based on their domino theory, thus, they couldn’t just risk the falling of a domino.

Reference
Bostdorff, D.M.(2008). Proclaiming the Truman Doctrine: the Cold War call to arms. Texas: Texas A&M University Press.