The answer to this question will always be debatable. Johnson has certainly received a heavy dose of blame for the war. However, the events that lead to the Unites States' military involvement in Vietnam were well underway before Johnson presidency.

The Vietnam War was an outgrowth of the Truman Doctrine, which promised to oppose the spread of communism around the world. Then, in 1956, President Eisenhower violated the Geneva Accords by creating the Southeast Asia Treaty Organization (SEATO) and backing Ngo Dinh Diem's refusal to hold elections. We will never know for sure what would have happened if Eisenhower had honored the Geneva Accords. Quite likely, Ho Chi Minh would have been elected as the leader of a united Vietnam that would have rejected American involvement. However, the prospect of a communist Vietnam was unpalatable to Western leaders. Then, shortly after the inauguration of President Kennedy in 1961, the new president increased the number of air sorties and military advisors in Vietnam in order to appear tough on communism.

When the communist forces of North Vietnam attempted to seize control of the whole country, Johnson felt that the United States could not neglect the commitment that it had already made in the region. It was the Johnson administration that was responsible for committing large numbers of American forces to Vietnam and escalating the conflict. At first, Johnson was reluctant to go boldly into Vietnam. Afraid to alienate potential political allies, Johnson escalated the war by a series of small degrees. This prevented an open debate on US involvement until the country was already fully committed. In this way, Johnson likely deserves a large degree of blame for escalating what could have been a smaller conflict into a full-fledged war.