The US had military advisers in Vietnam under Kennedy, but the was did not really start for the US Johnson became President.
Nixon.
President Eisenhower sent US advisers to Vietnam in 1955. President Kennedy sent US Special Forces (Green Beret) to Vietnam in 1961. President Johnson sent US regular forces to Vietnam in 1965.
President Gerald Ford
President Eisenhower sent US troops to Vietnam in 1955, President Ford pulled out the last US troops in 1975.
Eisenhower
The United States went into war with Vietnam in the year 1965.
President Johnson believed that the US could defeat north Vietnam because the US had won WWII with firepower, and the US had the most firepower on earth during the Vietnam War.
John Fitzgerald Kennedy
It was president Richard Nixon who finally pulled all U.S troops from Vietnam.
In the 1950s and 1960s Eisenhower and Kennedy sent US soldiers to South Vietnam. In 1965 President Johnson sent the US Marines.