Lyndon B Johnson
to increase the number of American troops and bombing campaigns in Vietnam.
Over 500,000
When President Nixon took office there was approximately 536,100 American troops in Vietnam. President Nixon immediately started reducing the number of troops in Vietnam.
I believe that was Lyndon B. Johnson. America's involvement in Vietnam was limited until he became president. According to Wikipedia, "It was Johnson who began America's direct involvement in the ground war in Vietnam." See the Related Links below for more information.
Over two and a half million men.
President Lyndon B. Johnson was directly linked to the dramatic increase in the number of troops deployed to Vietnam in the mid-1960s
Only a very limited number of "observers".
The Philippines sent support troops to Vietnam.
Environmental Protection Agency; normalization of relations with China; Watergate; increased bombing and decreased ground troops in Vietnam
Eisenhower first dispatched US Troops to RVN in February 1955.
President Kennedy sent additional US Advisers & Special Forces (Green Berets) to Vietnam in 1961 up thru 1962. Regular US combat troops did not arrive (officially) until 1965 under President Johnson. Since JFK had troops covertly already arriving in Vietnam by March or April of 1961, he must have ordered them about on his inauguration day of Jan.20, 1961, since it takes a month or two at best/quickest for that to happen...