The most important reason as to why the United States became involved in Vietnam was the long term cause of the Domino Theory. The Domino Theory was the belief that once one country had fallen to communism, its neighbours would do the same. It was devised by John Foster Dulles, the US Secretary of State, during the 1950s. The Domino Theory would be a an obstacle for the Americans if they were to win the Cold War, as they had to keep as few countries from going communist as possible. If South Vietnam were to fall communist, its neighbours in South East Asia may do the same- including India, a country with a billion inhabitants and around 90% of its people living in poverty.
Communism may look an attractive prospect to South East Asia’s poor, which increases the likelihood of the Domino Theory, and would have a dire effect for American economic interests in the region. American companies would be nationalised by the state under communism, and trade would be badly affected because Americans would not be able to sell commodities in communist countries. This would not only harm America’s economy, but also its military- it would not be able to sustain a well trained, well equipped army without the money to do so.
Eventually, this would also have dire political effects for America- its President would look weak, and the Soviet Union would be the dominant global power, due to the United States’ inferior military, economy and financial system. Moreover, if the Domino Theory proved correct, and South East Asia was to turn communist upon South Vietnam’s transition to communism, the American lives lost in the Korean War- a bloody conflict resulting in 142,000 US casualties that also involved communist North Korea fighting the capitalist, US backed South Korea in a bid to ‘contain’ communism- would be in vain.
This would be because their efforts to contain the spread of communism in Asia would be rendered almost useless if South East Asia were to become communist ten years after the Korean war. The ideas of a damaged US economy and military and the consequences this would bring for the Cold War, plus the lives given in vain in Korea were part of the worries of the Domino Theory, and were extremely important reasons as to why the United States became increasingly involved in the war in Vietnam.
Another important long term reason as to why the United States became increasingly involved in the war in Vietnam was the economic and military reason of the strategic importance of Vietnam. Vietnam bordered southern China, a communist and nuclear armed foe of the United States. Having an ally like South Vietnam would be of paramount importance if nuclear war broke out and the United States had nuclear warheads installed mere hundreds of miles below China and within range of south eastern Russia. Moreover, South Vietnam would be a good military ally to have if conventional warfare broke out- ships and planes from US installed naval and air bases would be able to navigate to China with relative ease due to the two countries’ proximity. The economic importance of Vietnam was also vital to US interests.
Without Vietnamese co-operation in the South China Sea, the United States would lose access to vital shipping lanes that allowed the import and export of goods from the United States to South East Asia, India and the Middle East. If America were to lose Vietnam, it would have to consider alternative trade routes, which may prove too costly in terms of money, fuel and time. It was not just Vietnam’s strategic importance that determined US involvement in Vietnam, but also the strategic importance of South East Asia as a whole, which the Americans thought they would lose to communism if Vietnam turned communist (due to the Domino Theory). The military and economic strategic importance of Vietnam (and South East Asia as a whole) is therefore an important long term reason as to why the United States became increasingly involved in the war in Vietnam.
An important short term reason as to why the United States became increasingly involved in Vietnam was the increasing danger and support of the National Liberation Front (NLF). The NLF, often referred to as the ‘Vietcong’ by their American counterparts, were a communist guerrilla organization that used non-conventional tactics to attack Diem’s capitalist government and the United States in South Vietnam. They were an armed group to counter the unpopularity of the South Vietnamese dictator, President Diem and aimed to reunify Vietnam under a communist government. Frustrated by the reforms that Catholic Diem was implementing in South Vietnam- persecution of the Buddhist majority, imprisonment of adult and children opponents to Diem’s rule, little money on social reform- the NLF decided to terrorise the South Vietnamese government.