What was the basis for the conflict in Vietnam?

In 1954, the Vietminh forces of Vietnam defeated the French at the Battle of Dien Bien Phu, and the nation was temporarily divided into two sections, north and south. The people of the south chose Ngo Dinh Diem as their ruler and Ho Chi Minh ruled the north. Diem refused to go along with the planned elections in 1956 to unite the nation so the Vietminh members in the south created the Viet Cong and the war between north and south for control of the country began. The government of South Vietnam requested military advisors from the United States to help train the South Vietnamese army. Ho Chi Minh was a communist and during the Cold War of the 1950s and 60s, the aim of the US government was containment of communist power and not to let it spread. The Eisenhower administration provided South Vietnam with money and advisors to help stop the threat of a North Vietnamese takeover. The United States also was pledged by treaty (SEATO) to aid the member nations in southeast Asia, if they were attacked by a foreign (communist) power. Following the Eisenhower and Kennedy administrations, President Lyndon B. Johnson also believed in containment and the domino theory. If one nation falls to communism, the next nation will fall, and the next, etc. It became the aim of the Johnson administration to prevent a communist takeover in Southeast Asia. Also, there were natural resources in the area, like oil, that the US did not want to fall into the hands of the Communits nations. In August, 1964, President Johnson reported to the nation that American ships had been attacked by North Vietnam gunboats in the Gulf of Tonkin, in international waters. The Congress passed the Gulf of Tonkin Resolution giving the President the power to use whatever force necessary to protect our interests in the area. At the time, the truth was not reported.