The US had military advisers in Vietnam under Kennedy, but the was did not really start for the US Johnson became President.
John Fitzgerald Kennedy
President Kennedy believed in the "Domino Theory" that required Communism to be contained in every instance. Therefore in his first speech on becoming president, Kennedy made it clear that he would continue the policy of the former President, Dwight Eisenhower, and support the government of Diem in South Vietnam.
'61
He was president during the cold war and vietnam.
During the Vietnam War, Presidents Kennedy and then Johnson were democrats.
I think Kennedy is the answer you are seeking. Eisenhower started the US involvement in Vietnam and Kennedy sent in more people to train pilots and such .
When Nixon ordered "military trainers" to Vietnam, the U.S. then started to become actively involved in Vietnam combat.
John Fitzgerald Kennedy
Kennedy.
The vietcong strikes convinced President Kennedy to send American military advisers to South Vietnam
US Army General Maxwell Taylor went to Vietnam, and on 01 November 1961 wrote a letter to President Kennedy recommending US Troops for Vietnam.
John F. Kennedy
Eisenhower, Kennedy, Johnson, Nixon, Ford.
'61
President Kennedy believed in the "Domino Theory" that required Communism to be contained in every instance. Therefore in his first speech on becoming president, Kennedy made it clear that he would continue the policy of the former President, Dwight Eisenhower, and support the government of Diem in South Vietnam.
He was president during the cold war and vietnam.